21972775 has 12 divisors (see below), whose sum is σ = 29723544. Its totient is φ = 15980000.

The previous prime is 21972763. The next prime is 21972803. The reversal of 21972775 is 57727912.

It is a happy number.

It is not a de Polignac number, because 21972775 - 2⁷ = 21972647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39676 + ... + 40225.

It is an arithmetic number, because the mean of its divisors is an integer number (2476962).

Almost surely, 2^21972775 is an apocalyptic number.

21972775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21972775 is a deficient number, since it is larger than the sum of its proper divisors (7750769).

21972775 is a wasteful number, since it uses less digits than its factorization.

21972775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79922 (or 79917 counting only the distinct ones).

The product of its digits is 61740, while the sum is 40.

The square root of 21972775 is about 4687.5126666496. The cubic root of 21972775 is about 280.0883012319.

The spelling of 21972775 in words is "twenty-one million, nine hundred seventy-two thousand, seven hundred seventy-five".