21972566 has 32 divisors (see below), whose sum is σ = 41783040. Its totient is φ = 8416800.

The previous prime is 21972553. The next prime is 21972593. The reversal of 21972566 is 66527912.

It is a happy number.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 8225 + ... + 10563.

It is an arithmetic number, because the mean of its divisors is an integer number (1305720).

Almost surely, 2^21972566 is an apocalyptic number.

21972566 is a deficient number, since it is larger than the sum of its proper divisors (19810474).

21972566 is a wasteful number, since it uses less digits than its factorization.

21972566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2420.

The product of its digits is 45360, while the sum is 38.

The square root of 21972566 is about 4687.4903733234. The cubic root of 21972566 is about 280.0874131838.

The spelling of 21972566 in words is "twenty-one million, nine hundred seventy-two thousand, five hundred sixty-six".