21888986 has 24 divisors (see below), whose sum is σ = 38358036. Its totient is φ = 9340800.

The previous prime is 21888973. The next prime is 21888989. The reversal of 21888986 is 68988812.

It can be written as a sum of positive squares in 2 ways, for example, as 21669025 + 219961 = 4655^2 + 469^2 .

It is not an unprimeable number, because it can be changed into a prime (21888989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39020 + ... + 39576.

Almost surely, 2^21888986 is an apocalyptic number.

21888986 is a deficient number, since it is larger than the sum of its proper divisors (16469050).

21888986 is a wasteful number, since it uses less digits than its factorization.

21888986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974 (or 967 counting only the distinct ones).

The product of its digits is 442368, while the sum is 50.

The square root of 21888986 is about 4678.5666608482. The cubic root of 21888986 is about 279.7318265689.

Adding to 21888986 its sum of digits (50), we get a triangular number (21889036 = T₆₆₁₆).

The spelling of 21888986 in words is "twenty-one million, eight hundred eighty-eight thousand, nine hundred eighty-six".