21974957 has 2 divisors, whose sum is σ = 21974958. Its totient is φ = 21974956.

The previous prime is 21974951. The next prime is 21974977. The reversal of 21974957 is 75947912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21771556 + 203401 = 4666^2 + 451^2 .

It is a cyclic number.

It is not a de Polignac number, because 21974957 - 2⁴ = 21974941 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21974951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10987478 + 10987479.

It is an arithmetic number, because the mean of its divisors is an integer number (10987479).

Almost surely, 2^21974957 is an apocalyptic number.

It is an amenable number.

21974957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21974957 is an equidigital number, since it uses as much as digits as its factorization.

21974957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 158760, while the sum is 44.

The square root of 21974957 is about 4687.7454069094. The cubic root of 21974957 is about 280.0975722873.

The spelling of 21974957 in words is "twenty-one million, nine hundred seventy-four thousand, nine hundred fifty-seven".