21991202417856 has 84 divisors (see below), whose sum is σ = 67684657470648. Its totient is φ = 6283200688128.

The previous prime is 21991202417813. The next prime is 21991202417879. The reversal of 21991202417856 is 65871420219912.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (84).

It is a super-2 number, since 2×21991202417856² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21991202417796 and 21991202417805.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1168740721 + ... + 1168759536.

Almost surely, 2^{21991202417856} is an apocalyptic number.

It is an amenable number.

21991202417856 is an abundant number, since it is smaller than the sum of its proper divisors (45693455052792).

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

21991202417856 is a wasteful number, since it uses less digits than its factorization.

21991202417856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2337500286 (or 2337500269 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 57.

The spelling of 21991202417856 in words is "twenty-one trillion, nine hundred ninety-one billion, two hundred two million, four hundred seventeen thousand, eight hundred fifty-six".