21991135877952 has 56 divisors (see below), whose sum is σ = 58187364988512. Its totient is φ = 7330065600000.

The previous prime is 21991135877903. The next prime is 21991135878017. The reversal of 21991135877952 is 25977853119912.

It is a super-2 number, since 2×21991135877952² (a number of 27 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, 2084202 + ... + 6951702.

Almost surely, 2^{21991135877952} is an apocalyptic number.

It is an amenable number.

21991135877952 is an abundant number, since it is smaller than the sum of its proper divisors (36196229110560).

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

21991135877952 is a wasteful number, since it uses less digits than its factorization.

21991135877952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4891047 (or 4891037 counting only the distinct ones).

The product of its digits is 85730400, while the sum is 69.

The spelling of 21991135877952 in words is "twenty-one trillion, nine hundred ninety-one billion, one hundred thirty-five million, eight hundred seventy-seven thousand, nine hundred fifty-two".