21865992 has 32 divisors (see below), whose sum is σ = 54794400. Its totient is φ = 7271424.

The previous prime is 21865981. The next prime is 21865993. The reversal of 21865992 is 29956812.

It is a super-2 number, since 2×21865992² = 956243212288128, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21865993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13059 + ... + 14637.

It is an arithmetic number, because the mean of its divisors is an integer number (1712325).

Almost surely, 2^21865992 is an apocalyptic number.

It is an amenable number.

21865992 is an abundant number, since it is smaller than the sum of its proper divisors (32928408).

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

21865992 is a wasteful number, since it uses less digits than its factorization.

21865992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2165 (or 2161 counting only the distinct ones).

The product of its digits is 77760, while the sum is 42.

The square root of 21865992 is about 4676.1086386011. The cubic root of 21865992 is about 279.6338411068.

The spelling of 21865992 in words is "twenty-one million, eight hundred sixty-five thousand, nine hundred ninety-two".