21160565 has 4 divisors (see below), whose sum is σ = 25392684. Its totient is φ = 16928448.

The previous prime is 21160553. The next prime is 21160571. The reversal of 21160565 is 56506112.

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 3301489 + 17859076 = 1817^2 + 4226^2 .

It is a cyclic number.

It is not a de Polignac number, because 21160565 - 2⁶ = 21160501 is a prime.

It is a super-2 number, since 2×21160565² = 895539022238450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent 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, 2116052 + ... + 2116061.

It is an arithmetic number, because the mean of its divisors is an integer number (6348171).

Almost surely, 2^21160565 is an apocalyptic number.

It is an amenable number.

21160565 is a deficient number, since it is larger than the sum of its proper divisors (4232119).

21160565 is an equidigital number, since it uses as much as digits as its factorization.

21160565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4232118.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21160565 is about 4600.0614126335. The cubic root of 21160565 is about 276.5937865485.

Adding to 21160565 its reverse (56506112), we get a palindrome (77666677).

The spelling of 21160565 in words is "twenty-one million, one hundred sixty thousand, five hundred sixty-five".