21256645392 has 60 divisors (see below), whose sum is σ = 59543462784. Its totient is φ = 7079071680.

The previous prime is 21256645381. The next prime is 21256645477. The reversal of 21256645392 is 29354665212.

21256645392 is a `hidden beast` number, since 2 + 1 + 2 + 56 + 64 + 539 + 2 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 91917 + ... + 225747.

Almost surely, 2^21256645392 is an apocalyptic number.

It is an amenable number.

21256645392 is an abundant number, since it is smaller than the sum of its proper divisors (38286817392).

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

21256645392 is a wasteful number, since it uses less digits than its factorization.

21256645392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134948 (or 134939 counting only the distinct ones).

The product of its digits is 777600, while the sum is 45.

The spelling of 21256645392 in words is "twenty-one billion, two hundred fifty-six million, six hundred forty-five thousand, three hundred ninety-two".