21972879 has 6 divisors (see below), whose sum is σ = 31738616. Its totient is φ = 14648580.

The previous prime is 21972869. The next prime is 21972901. The reversal of 21972879 is 97827912.

It is not a de Polignac number, because 21972879 - 2¹² = 21968783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21972809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1220707 + ... + 1220724.

Almost surely, 2^21972879 is an apocalyptic number.

21972879 is a deficient number, since it is larger than the sum of its proper divisors (9765737).

21972879 is a wasteful number, since it uses less digits than its factorization.

21972879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2441437 (or 2441434 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21972879 is about 4687.5237599398. The cubic root of 21972879 is about 280.0887431293.

The spelling of 21972879 in words is "twenty-one million, nine hundred seventy-two thousand, eight hundred seventy-nine".