21365713 has 6 divisors (see below), whose sum is σ = 21698502. Its totient is φ = 21034080.

The previous prime is 21365699. The next prime is 21365723. The reversal of 21365713 is 31756312.

It can be written as a sum of positive squares in 3 ways, for example, as 2155024 + 19210689 = 1468^2 + 4383^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21365713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21365723) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 39223 + ... + 39763.

It is an arithmetic number, because the mean of its divisors is an integer number (3616417).

Almost surely, 2^21365713 is an apocalyptic number.

It is an amenable number.

21365713 is a deficient number, since it is larger than the sum of its proper divisors (332789).

21365713 is an frugal number, since it uses more digits than its factorization.

21365713 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155 (or 614 counting only the distinct ones).

The product of its digits is 3780, while the sum is 28.

The square root of 21365713 is about 4622.3060262168. The cubic root of 21365713 is about 277.4847563523.

The spelling of 21365713 in words is "twenty-one million, three hundred sixty-five thousand, seven hundred thirteen".