21648408256225 has 27 divisors (see below), whose sum is σ = 28062596270163. Its totient is φ = 16565329046640.

The previous prime is 21648408256207. The next prime is 21648408256249. The reversal of 21648408256225 is 52265280484612.

The square root of 21648408256225 is 4652785.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 7793426972241 + 13854981283984 = 2791671^2 + 3722228^2 .

It is not a de Polignac number, because 21648408256225 - 2⁵ = 21648408256193 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 535050046 + ... + 535090504.

Almost surely, 2^{21648408256225} is an apocalyptic number.

21648408256225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21648408256225 is the 4652785-th square number.

21648408256225 is the 2326393-rd centered octagonal number.

It is an amenable number.

21648408256225 is a deficient number, since it is larger than the sum of its proper divisors (6414188013938).

21648408256225 is an frugal number, since it uses more digits than its factorization.

21648408256225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80974 (or 40487 counting only the distinct ones).

The product of its (nonzero) digits is 14745600, while the sum is 55.

The spelling of 21648408256225 in words is "twenty-one trillion, six hundred forty-eight billion, four hundred eight million, two hundred fifty-six thousand, two hundred twenty-five".