21615844968 has 24 divisors (see below), whose sum is σ = 58542913650. Its totient is φ = 7205281632.

The previous prime is 21615844949. The next prime is 21615845029. The reversal of 21615844968 is 86944851612.

21615844968 is a `hidden beast` number, since 2 + 16 + 1 + 584 + 49 + 6 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19471969764 + 2143875204 = 139542^2 + 46302^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21615844968² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 150109963 + ... + 150110106.

Almost surely, 2^21615844968 is an apocalyptic number.

It is an amenable number.

21615844968 is an abundant number, since it is smaller than the sum of its proper divisors (36927068682).

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

21615844968 is a wasteful number, since it uses less digits than its factorization.

21615844968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300220081 (or 300220074 counting only the distinct ones).

The product of its digits is 3317760, while the sum is 54.

The spelling of 21615844968 in words is "twenty-one billion, six hundred fifteen million, eight hundred forty-four thousand, nine hundred sixty-eight".