21037631 has 2 divisors, whose sum is σ = 21037632. Its totient is φ = 21037630.

The previous prime is 21037609. The next prime is 21037649. The reversal of 21037631 is 13673012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21037631 - 2⁶ = 21037567 is a prime.

It is a super-2 number, since 2×21037631² = 885163836184322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21037597 and 21037606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21037231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10518815 + 10518816.

It is an arithmetic number, because the mean of its divisors is an integer number (10518816).

Almost surely, 2^21037631 is an apocalyptic number.

21037631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21037631 is an equidigital number, since it uses as much as digits as its factorization.

21037631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 756, while the sum is 23.

The square root of 21037631 is about 4586.6797359310. The cubic root of 21037631 is about 276.0571146591.

The spelling of 21037631 in words is "twenty-one million, thirty-seven thousand, six hundred thirty-one".