21863880 has 48 divisors (see below), whose sum is σ = 71058780. Its totient is φ = 5830272.

The previous prime is 21863879. The next prime is 21863893. The reversal of 21863880 is 8836812.

21863880 is a `hidden beast` number, since 2 + 18 + 638 + 8 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 21511044 + 352836 = 4638^2 + 594^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30007 + ... + 30726.

Almost surely, 2^21863880 is an apocalyptic number.

21863880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21863880 is an abundant number, since it is smaller than the sum of its proper divisors (49194900).

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

21863880 is a wasteful number, since it uses less digits than its factorization.

21863880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60750 (or 60743 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21863880 is about 4675.8828043483. The cubic root of 21863880 is about 279.6248376936.

The spelling of 21863880 in words is "twenty-one million, eight hundred sixty-three thousand, eight hundred eighty".