21807265 has 8 divisors (see below), whose sum is σ = 26245800. Its totient is φ = 17394432.

The previous prime is 21807259. The next prime is 21807271. The reversal of 21807265 is 56270812.

It is an interprime number because it is at equal distance from previous prime (21807259) and next prime (21807271).

It can be written as a sum of positive squares in 4 ways, for example, as 4309776 + 17497489 = 2076^2 + 4183^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21807265 - 2³ = 21807257 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4504 + ... + 7993.

It is an arithmetic number, because the mean of its divisors is an integer number (3280725).

Almost surely, 2^21807265 is an apocalyptic number.

It is an amenable number.

21807265 is a deficient number, since it is larger than the sum of its proper divisors (4438535).

21807265 is a wasteful number, since it uses less digits than its factorization.

21807265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12851.

The product of its (nonzero) digits is 6720, while the sum is 31.

The square root of 21807265 is about 4669.8249431858. The cubic root of 21807265 is about 279.3832726974.

The spelling of 21807265 in words is "twenty-one million, eight hundred seven thousand, two hundred sixty-five".