21724986 has 32 divisors (see below), whose sum is σ = 45121536. Its totient is φ = 6966000.

The previous prime is 21724943. The next prime is 21724991. The reversal of 21724986 is 68942712.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50191 + ... + 50621.

It is an arithmetic number, because the mean of its divisors is an integer number (1410048).

Almost surely, 2^21724986 is an apocalyptic number.

21724986 is an abundant number, since it is smaller than the sum of its proper divisors (23396550).

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

21724986 is a wasteful number, since it uses less digits than its factorization.

21724986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738.

The product of its digits is 48384, while the sum is 39.

The square root of 21724986 is about 4661.0069727474. The cubic root of 21724986 is about 279.0314580220.

The spelling of 21724986 in words is "twenty-one million, seven hundred twenty-four thousand, nine hundred eighty-six".