21256908364872 has 96 divisors (see below), whose sum is σ = 59564909547000. Its totient is φ = 6840279613440.

The previous prime is 21256908364859. The next prime is 21256908364883. The reversal of 21256908364872 is 27846380965212.

21256908364872 is a `hidden beast` number, since 2 + 1 + 2 + 569 + 0 + 8 + 3 + 64 + 8 + 7 + 2 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 20800221647076 + 456686717796 = 4560726^2 + 675786^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13249672 + ... + 14767112.

It is a 1-persistent number, because it is pandigital, but 2⋅21256908364872 = 42513816729744 is not.

Almost surely, 2^{21256908364872} is an apocalyptic number.

It is an amenable number.

21256908364872 is an abundant number, since it is smaller than the sum of its proper divisors (38308001182128).

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

21256908364872 is a wasteful number, since it uses less digits than its factorization.

21256908364872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1524191 (or 1524184 counting only the distinct ones).

The product of its (nonzero) digits is 69672960, while the sum is 63.

The spelling of 21256908364872 in words is "twenty-one trillion, two hundred fifty-six billion, nine hundred eight million, three hundred sixty-four thousand, eight hundred seventy-two".