21256908 has 24 divisors (see below), whose sum is σ = 49674240. Its totient is φ = 7074960.

The previous prime is 21256867. The next prime is 21256909. The reversal of 21256908 is 80965212.

It is a super-2 number, since 2×21256908² = 903712275440928, which contains 22 as substring.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21256909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14053 + ... + 15491.

It is an arithmetic number, because the mean of its divisors is an integer number (2069760).

Almost surely, 2^21256908 is an apocalyptic number.

It is an amenable number.

21256908 is an abundant number, since it is smaller than the sum of its proper divisors (28417332).

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

21256908 is a wasteful number, since it uses less digits than its factorization.

21256908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2677 (or 2675 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21256908 is about 4610.5214455634. The cubic root of 21256908 is about 277.0129236716.

The spelling of 21256908 in words is "twenty-one million, two hundred fifty-six thousand, nine hundred eight".