21164265 has 12 divisors (see below), whose sum is σ = 36684804. Its totient is φ = 11287584.

The previous prime is 21164239. The next prime is 21164281. The reversal of 21164265 is 56246112.

21164265 is a `hidden beast` number, since 2 + 11 + 642 + 6 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 3549456 + 17614809 = 1884^2 + 4197^2 .

It is not a de Polignac number, because 21164265 - 2¹¹ = 21162217 is a prime.

It is a super-2 number, since 2×21164265² = 895852225980450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 235114 + ... + 235203.

It is an arithmetic number, because the mean of its divisors is an integer number (3057067).

Almost surely, 2^21164265 is an apocalyptic number.

It is an amenable number.

21164265 is a deficient number, since it is larger than the sum of its proper divisors (15520539).

21164265 is a wasteful number, since it uses less digits than its factorization.

21164265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470328 (or 470325 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21164265 is about 4600.4635635988. The cubic root of 21164265 is about 276.6099067446.

The spelling of 21164265 in words is "twenty-one million, one hundred sixty-four thousand, two hundred sixty-five".