• 145 can be written using four 4's:
145 has 4 divisors (see below), whose sum is σ = 180. Its totient is φ = 112.
The previous prime is 139. The next prime is 149. The reversal of 145 is 541.
145 is nontrivially palindromic in base 9 and base 12.
It is a Cunningham number, because it is equal to 122+1.
145 is an esthetic number in base 3, base 4, base 12 and base 15, because in such bases its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 64 + 81 = 8^2 + 9^2 .
It is a cyclic number.
It is not a de Polignac number, because 145 - 23 = 137 is a prime.
It is a Leyland number of the form 43 + 34.
It is an Ulam number.
It is an alternating number because its digits alternate between odd and even.
145 is an undulating number in base 9 and base 12.
It is a plaindrome in base 10, base 11 and base 15.
It is a nialpdrome in base 8, base 13, base 14 and base 16.
It is a congruent number.
It is a pernicious number, because its binary representation contains a prime number (3) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10 + ... + 19.
It is an arithmetic number, because the mean of its divisors is an integer number (45).
It is a Proth number, since it is equal to 9 ⋅ 24 + 1 and 9 < 24.
145 is the 10-th pentagonal number.
145 is the 9-th centered square number.
It is an amenable number.
145 is a deficient number, since it is larger than the sum of its proper divisors (35).
145 is an equidigital number, since it uses as much as digits as its factorization.
145 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 20, while the sum is 10.
The square root of 145 is about 12.0415945788. The cubic root of 145 is about 5.2535878725.
Subtracting from 145 its product of digits (20), we obtain a cube (125 = 53).
Adding to 145 its reverse (541), we get a palindrome (686).
The spelling of 145 in words is "one hundred forty-five", and thus it is an aban number.
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