21373431 has 4 divisors (see below), whose sum is σ = 28497912. Its totient is φ = 14248952.

The previous prime is 21373411. The next prime is 21373447. The reversal of 21373431 is 13437312.

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 21373431 - 2¹⁵ = 21340663 is a prime.

It is a super-2 number, since 2×21373431² = 913647105423522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21373411) 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, 3562236 + ... + 3562241.

It is an arithmetic number, because the mean of its divisors is an integer number (7124478).

Almost surely, 2^21373431 is an apocalyptic number.

21373431 is a deficient number, since it is larger than the sum of its proper divisors (7124481).

21373431 is an equidigital number, since it uses as much as digits as its factorization.

21373431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7124480.

The product of its digits is 1512, while the sum is 24.

The square root of 21373431 is about 4623.1408155063. The cubic root of 21373431 is about 277.5181645443.

The spelling of 21373431 in words is "twenty-one million, three hundred seventy-three thousand, four hundred thirty-one".