• 253 can be written using four 4's:
253 has 4 divisors (see below), whose sum is σ = 288. Its totient is φ = 220.
The previous prime is 251. The next prime is 257. The reversal of 253 is 352.
253 is nontrivially palindromic in base 12 and base 14.
It is the 7-th star number.
253 is an esthetic number in base 11, because in such base its adjacent digits differ by 1.
253 is a nontrivial binomial coefficient, being equal to C(23, 2).
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.
It is not a de Polignac number, because 253 - 21 = 251 is a prime.
253 is an idoneal number.
It is an Ulam number.
It is a Duffinian number.
253 is an undulating number in base 12 and base 14.
It is a plaindrome in base 13 and base 15.
It is a nialpdrome in base 4, base 7, base 9, base 11 and base 16.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (251) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 22.
It is an arithmetic number, because the mean of its divisors is an integer number (72).
253 is a gapful number since it is divisible by the number (23) formed by its first and last digit.
253 is the 22-nd triangular number.
253 is the 9-th centered heptagonal number and also the 8-th centered nonagonal number.
It is an amenable number.
253 is a deficient number, since it is larger than the sum of its proper divisors (35).
253 is a wasteful number, since it uses less digits than its factorization.
253 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 34.
The product of its digits is 30, while the sum is 10.
The square root of 253 is about 15.9059737206. The cubic root of 253 is about 6.3247035434.
Subtracting from 253 its sum of digits (10), we obtain a 5-th power (243 = 35).
Subtracting 253 from its reverse (352), we obtain a palindrome (99).
It can be divided in two parts, 25 and 3, that added together give a triangular number (28 = T7).
The spelling of 253 in words is "two hundred fifty-three", and thus it is an aban number.
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