21256709376 has 72 divisors (see below), whose sum is σ = 64655840704. Its totient is φ = 6073344000.

The previous prime is 21256709347. The next prime is 21256709387. The reversal of 21256709376 is 67390765212.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1971625 + ... + 1982376.

Almost surely, 2^21256709376 is an apocalyptic number.

It is an amenable number.

21256709376 is an abundant number, since it is smaller than the sum of its proper divisors (43399131328).

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

21256709376 is an equidigital number, since it uses as much as digits as its factorization.

21256709376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3954027 (or 3954013 counting only the distinct ones).

The product of its (nonzero) digits is 952560, while the sum is 48.

The spelling of 21256709376 in words is "twenty-one billion, two hundred fifty-six million, seven hundred nine thousand, three hundred seventy-six".