21972986 has 32 divisors (see below), whose sum is σ = 39232512. Its totient is φ = 9031680.

The previous prime is 21972971. The next prime is 21972997. The reversal of 21972986 is 68927912.

It is a happy number.

It is a super-2 number, since 2×21972986² = 965624227512392, which contains 22 as substring.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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, 85370 + ... + 85626.

It is an arithmetic number, because the mean of its divisors is an integer number (1226016).

Almost surely, 2^21972986 is an apocalyptic number.

21972986 is a deficient number, since it is larger than the sum of its proper divisors (17259526).

21972986 is a wasteful number, since it uses less digits than its factorization.

21972986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494.

The product of its digits is 108864, while the sum is 44.

The square root of 21972986 is about 4687.5351732014. The cubic root of 21972986 is about 280.0891977723.

The spelling of 21972986 in words is "twenty-one million, nine hundred seventy-two thousand, nine hundred eighty-six".