21075451656 has 32 divisors (see below), whose sum is σ = 60215576640. Its totient is φ = 6021557568.

The previous prime is 21075451591. The next prime is 21075451679. The reversal of 21075451656 is 65615457012.

It is a Harshad number since it is a multiple of its sum of digits (42).

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, 62724391 + ... + 62724726.

It is an arithmetic number, because the mean of its divisors is an integer number (1881736770).

Almost surely, 2^21075451656 is an apocalyptic number.

It is an amenable number.

21075451656 is an abundant number, since it is smaller than the sum of its proper divisors (39140124984).

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

21075451656 is a wasteful number, since it uses less digits than its factorization.

21075451656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125449133 (or 125449129 counting only the distinct ones).

The product of its (nonzero) digits is 252000, while the sum is 42.

The spelling of 21075451656 in words is "twenty-one billion, seventy-five million, four hundred fifty-one thousand, six hundred fifty-six".