21373631 has 4 divisors (see below), whose sum is σ = 21497352. Its totient is φ = 21249912.

The previous prime is 21373591. The next prime is 21373657. The reversal of 21373631 is 13637312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21373631 - 2¹⁴ = 21357247 is a prime.

It is a super-2 number, since 2×21373631² = 913664204248322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21373631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21373691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61601 + ... + 61946.

It is an arithmetic number, because the mean of its divisors is an integer number (5374338).

Almost surely, 2^21373631 is an apocalyptic number.

21373631 is a deficient number, since it is larger than the sum of its proper divisors (123721).

21373631 is a wasteful number, since it uses less digits than its factorization.

21373631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123720.

The product of its digits is 2268, while the sum is 26.

The square root of 21373631 is about 4623.1624457724. The cubic root of 21373631 is about 277.5190301588.

The spelling of 21373631 in words is "twenty-one million, three hundred seventy-three thousand, six hundred thirty-one".