21568465 has 4 divisors (see below), whose sum is σ = 25882164. Its totient is φ = 17254768.

The previous prime is 21568433. The next prime is 21568471. The reversal of 21568465 is 56486512.

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 7006609 + 14561856 = 2647^2 + 3816^2 .

It is a cyclic number.

It is not a de Polignac number, because 21568465 - 2⁵ = 21568433 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2156842 + ... + 2156851.

It is an arithmetic number, because the mean of its divisors is an integer number (6470541).

Almost surely, 2^21568465 is an apocalyptic number.

It is an amenable number.

21568465 is a deficient number, since it is larger than the sum of its proper divisors (4313699).

21568465 is an equidigital number, since it uses as much as digits as its factorization.

21568465 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4313698.

The product of its digits is 57600, while the sum is 37.

The square root of 21568465 is about 4644.1861504466. The cubic root of 21568465 is about 278.3597339112.

The spelling of 21568465 in words is "twenty-one million, five hundred sixty-eight thousand, four hundred sixty-five".