21156844028 has 24 divisors (see below), whose sum is σ = 37091040000. Its totient is φ = 10559425968.

The previous prime is 21156844019. The next prime is 21156844039. The reversal of 21156844028 is 82044865112.

It is a super-2 number, since 2×21156844028² (a number of 21 digits) contains 22 as substring.

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, 7955363 + ... + 7958021.

It is an arithmetic number, because the mean of its divisors is an integer number (1545460000).

Almost surely, 2^21156844028 is an apocalyptic number.

It is an amenable number.

21156844028 is a deficient number, since it is larger than the sum of its proper divisors (15934195972).

21156844028 is a wasteful number, since it uses less digits than its factorization.

21156844028 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5489 (or 5487 counting only the distinct ones).

The product of its (nonzero) digits is 122880, while the sum is 41.

The spelling of 21156844028 in words is "twenty-one billion, one hundred fifty-six million, eight hundred forty-four thousand, twenty-eight".