21231937 has 2 divisors, whose sum is σ = 21231938. Its totient is φ = 21231936.

The previous prime is 21231923. The next prime is 21231941. The reversal of 21231937 is 73913212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19044496 + 2187441 = 4364^2 + 1479^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21231937 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21234937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615968 + 10615969.

It is an arithmetic number, because the mean of its divisors is an integer number (10615969).

Almost surely, 2^21231937 is an apocalyptic number.

It is an amenable number.

21231937 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231937 is an equidigital number, since it uses as much as digits as its factorization.

21231937 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 28.

The square root of 21231937 is about 4607.8126046965. The cubic root of 21231937 is about 276.9044099260.

The spelling of 21231937 in words is "twenty-one million, two hundred thirty-one thousand, nine hundred thirty-seven".