21255256 has 16 divisors (see below), whose sum is σ = 43476840. Its totient is φ = 9661440.

The previous prime is 21255239. The next prime is 21255257. The reversal of 21255256 is 65255212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120681 + ... + 120856.

Almost surely, 2^21255256 is an apocalyptic number.

It is an amenable number.

21255256 is an abundant number, since it is smaller than the sum of its proper divisors (22221584).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21255256 is a wasteful number, since it uses less digits than its factorization.

21255256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241554 (or 241550 counting only the distinct ones).

The product of its digits is 6000, while the sum is 28.

The square root of 21255256 is about 4610.3422866421. The cubic root of 21255256 is about 277.0057473817.

It can be divided in two parts, 2125 and 5256, that added together give a triangular number (7381 = T₁₂₁).

The spelling of 21255256 in words is "twenty-one million, two hundred fifty-five thousand, two hundred fifty-six".