21285253 has 8 divisors (see below), whose sum is σ = 23614560. Its totient is φ = 19021680.

The previous prime is 21285247. The next prime is 21285269. The reversal of 21285253 is 35258212.

21285253 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21285253 - 2⁹ = 21284741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21285203) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15750 + ... + 17047.

It is an arithmetic number, because the mean of its divisors is an integer number (2951820).

Almost surely, 2^21285253 is an apocalyptic number.

It is an amenable number.

21285253 is a deficient number, since it is larger than the sum of its proper divisors (2329307).

21285253 is a wasteful number, since it uses less digits than its factorization.

21285253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32867.

The product of its digits is 4800, while the sum is 28.

The square root of 21285253 is about 4613.5943688192. The cubic root of 21285253 is about 277.1359965076.

It can be divided in two parts, 2128 and 5253, that added together give a triangular number (7381 = T₁₂₁).

The spelling of 21285253 in words is "twenty-one million, two hundred eighty-five thousand, two hundred fifty-three".