21716565 has 32 divisors (see below), whose sum is σ = 39626496. Its totient is φ = 10060800.

The previous prime is 21716533. The next prime is 21716567. The reversal of 21716565 is 56561712.

It is not a de Polignac number, because 21716565 - 2⁵ = 21716533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21716567) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40 + ... + 6590.

It is an arithmetic number, because the mean of its divisors is an integer number (1238328).

Almost surely, 2^21716565 is an apocalyptic number.

It is an amenable number.

21716565 is a deficient number, since it is larger than the sum of its proper divisors (17909931).

21716565 is a wasteful number, since it uses less digits than its factorization.

21716565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6589.

The product of its digits is 12600, while the sum is 33.

The square root of 21716565 is about 4660.1035396223. The cubic root of 21716565 is about 278.9954008055.

The spelling of 21716565 in words is "twenty-one million, seven hundred sixteen thousand, five hundred sixty-five".