21972951 has 80 divisors (see below), whose sum is σ = 44233728. Its totient is φ = 10497600.

The previous prime is 21972917. The next prime is 21972961. The reversal of 21972951 is 15927912.

It is not a de Polignac number, because 21972951 - 2⁹ = 21972439 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21972901) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 80946 + ... + 81216.

Almost surely, 2^21972951 is an apocalyptic number.

21972951 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21972951 is an abundant number, since it is smaller than the sum of its proper divisors (22260777).

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

21972951 is a wasteful number, since it uses less digits than its factorization.

21972951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314 (or 305 counting only the distinct ones).

The product of its digits is 11340, while the sum is 36.

The square root of 21972951 is about 4687.5314398946. The cubic root of 21972951 is about 280.0890490575.

The spelling of 21972951 in words is "twenty-one million, nine hundred seventy-two thousand, nine hundred fifty-one".