21628498916025 has 27 divisors (see below), whose sum is σ = 38739169672879. Its totient is φ = 11535162216720.

The previous prime is 21628498915943. The next prime is 21628498916027. The reversal of 21628498916025 is 52061989482612.

The square root of 21628498916025 is 4650645.

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

21628498916025 is a `hidden beast` number, since 2 + 1 + 62 + 8 + 498 + 9 + 1 + 60 + 25 = 666.

It can be written as a sum of positive squares in only one way, i.e., 7786259609769 + 13842239306256 = 2790387^2 + 3720516^2 .

It is not a de Polignac number, because 21628498916025 - 2³⁷ = 21491059962553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21628498916027) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 69604654 + ... + 69914696.

Almost surely, 2^{21628498916025} is an apocalyptic number.

21628498916025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21628498916025 is the 4650645-th square number.

21628498916025 is the 2325323-rd centered octagonal number.

It is an amenable number.

21628498916025 is a deficient number, since it is larger than the sum of its proper divisors (17110670756854).

21628498916025 is an frugal number, since it uses more digits than its factorization.

21628498916025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 620102 (or 310051 counting only the distinct ones).

The product of its (nonzero) digits is 29859840, while the sum is 63.

The spelling of 21628498916025 in words is "twenty-one trillion, six hundred twenty-eight billion, four hundred ninety-eight million, nine hundred sixteen thousand, twenty-five".