21966565 has 16 divisors (see below), whose sum is σ = 28019520. Its totient is φ = 16485120.

The previous prime is 21966551. The next prime is 21966589. The reversal of 21966565 is 56566912.

It is not a de Polignac number, because 21966565 - 2⁹ = 21966053 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9085 + ... + 11245.

It is an arithmetic number, because the mean of its divisors is an integer number (1751220).

Almost surely, 2^21966565 is an apocalyptic number.

It is an amenable number.

21966565 is a deficient number, since it is larger than the sum of its proper divisors (6052955).

21966565 is a wasteful number, since it uses less digits than its factorization.

21966565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2292.

The product of its digits is 97200, while the sum is 40.

The square root of 21966565 is about 4686.8502216307. The cubic root of 21966565 is about 280.0619123296.

The spelling of 21966565 in words is "twenty-one million, nine hundred sixty-six thousand, five hundred sixty-five".