21373207656 has 32 divisors (see below), whose sum is σ = 53601596640. Its totient is φ = 7101925568.

The previous prime is 21373207651. The next prime is 21373207697. The reversal of 21373207656 is 65670237312.

It is not an unprimeable number, because it can be changed into a prime (21373207651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1397046 + ... + 1412261.

It is an arithmetic number, because the mean of its divisors is an integer number (1675049895).

Almost surely, 2^21373207656 is an apocalyptic number.

It is an amenable number.

21373207656 is an abundant number, since it is smaller than the sum of its proper divisors (32228388984).

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

21373207656 is a wasteful number, since it uses less digits than its factorization.

21373207656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2809633 (or 2809629 counting only the distinct ones).

The product of its (nonzero) digits is 317520, while the sum is 42.

The spelling of 21373207656 in words is "twenty-one billion, three hundred seventy-three million, two hundred seven thousand, six hundred fifty-six".