21155706655564 has 12 divisors (see below), whose sum is σ = 39870370235584. Its totient is φ = 9764172302544.

The previous prime is 21155706655547. The next prime is 21155706655571. The reversal of 21155706655564 is 46555660755112.

It is a super-2 number, since 2×21155706655564² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21155706655499 and 21155706655508.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203420256252 + ... + 203420256355.

Almost surely, 2^{21155706655564} is an apocalyptic number.

It is an amenable number.

21155706655564 is a deficient number, since it is larger than the sum of its proper divisors (18714663580020).

21155706655564 is a wasteful number, since it uses less digits than its factorization.

21155706655564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406840512624 (or 406840512622 counting only the distinct ones).

The product of its (nonzero) digits is 37800000, while the sum is 58.

The spelling of 21155706655564 in words is "twenty-one trillion, one hundred fifty-five billion, seven hundred six million, six hundred fifty-five thousand, five hundred sixty-four".