21912313 has 4 divisors (see below), whose sum is σ = 22667940. Its totient is φ = 21156688.

The previous prime is 21912311. The next prime is 21912347. The reversal of 21912313 is 31321912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6135529 + 15776784 = 2477^2 + 3972^2 .

It is a cyclic number.

It is not a de Polignac number, because 21912313 - 2¹ = 21912311 is a prime.

It is a super-2 number, since 2×21912313² = 960298922019938, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21912311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 377770 + ... + 377827.

It is an arithmetic number, because the mean of its divisors is an integer number (5666985).

Almost surely, 2^21912313 is an apocalyptic number.

It is an amenable number.

21912313 is a deficient number, since it is larger than the sum of its proper divisors (755627).

21912313 is an equidigital number, since it uses as much as digits as its factorization.

21912313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755626.

The product of its digits is 324, while the sum is 22.

The square root of 21912313 is about 4681.0589613890. The cubic root of 21912313 is about 279.8311609662.

The spelling of 21912313 in words is "twenty-one million, nine hundred twelve thousand, three hundred thirteen".