21456165 has 16 divisors (see below), whose sum is σ = 34387776. Its totient is φ = 11424000.

The previous prime is 21456157. The next prime is 21456167. The reversal of 21456165 is 56165412.

It is not a de Polignac number, because 21456165 - 2³ = 21456157 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456167) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15085 + ... + 16445.

It is an arithmetic number, because the mean of its divisors is an integer number (2149236).

Almost surely, 2^21456165 is an apocalyptic number.

It is an amenable number.

21456165 is a deficient number, since it is larger than the sum of its proper divisors (12931611).

21456165 is a wasteful number, since it uses less digits than its factorization.

21456165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2420.

The product of its digits is 7200, while the sum is 30.

The square root of 21456165 is about 4632.0799863560. The cubic root of 21456165 is about 277.8757834027.

The spelling of 21456165 in words is "twenty-one million, four hundred fifty-six thousand, one hundred sixty-five".