21735565 has 8 divisors (see below), whose sum is σ = 26575128. Its totient is φ = 17060160.

The previous prime is 21735533. The next prime is 21735577. The reversal of 21735565 is 56553712.

It can be written as a sum of positive squares in 4 ways, for example, as 10673289 + 11062276 = 3267^2 + 3326^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21735565 - 2⁵ = 21735533 is a prime.

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 21735565.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40746 + ... + 41275.

It is an arithmetic number, because the mean of its divisors is an integer number (3321891).

Almost surely, 2^21735565 is an apocalyptic number.

It is an amenable number.

21735565 is a deficient number, since it is larger than the sum of its proper divisors (4839563).

21735565 is an equidigital number, since it uses as much as digits as its factorization.

21735565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82079.

The product of its digits is 31500, while the sum is 34.

The square root of 21735565 is about 4662.1416752390. The cubic root of 21735565 is about 279.0767422059.

The spelling of 21735565 in words is "twenty-one million, seven hundred thirty-five thousand, five hundred sixty-five".