21557992 has 16 divisors (see below), whose sum is σ = 42179040. Its totient is φ = 10310256.

The previous prime is 21557983. The next prime is 21558001. The reversal of 21557992 is 29975512.

It is an interprime number because it is at equal distance from previous prime (21557983) and next prime (21558001).

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, 58398 + ... + 58765.

It is an arithmetic number, because the mean of its divisors is an integer number (2636190).

Almost surely, 2^21557992 is an apocalyptic number.

It is an amenable number.

21557992 is a deficient number, since it is larger than the sum of its proper divisors (20621048).

21557992 is a wasteful number, since it uses less digits than its factorization.

21557992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117192 (or 117188 counting only the distinct ones).

The product of its digits is 56700, while the sum is 40.

The square root of 21557992 is about 4643.0584747556. The cubic root of 21557992 is about 278.3146722362.

The spelling of 21557992 in words is "twenty-one million, five hundred fifty-seven thousand, nine hundred ninety-two".