21005676408025 has 27 divisors (see below), whose sum is σ = 26915280154173. Its totient is φ = 16261909171200.

The previous prime is 21005676408001. The next prime is 21005676408029. The reversal of 21005676408025 is 52080467650012.

The square root of 21005676408025 is 4583195.

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

It can be written as a sum of positive squares in 4 ways, for example, as 238297256649 + 20767379151376 = 488157^2 + 4557124^2 .

It is not a de Polignac number, because 21005676408025 - 2¹³ = 21005676399833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21005676408029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 710380441 + ... + 710410009.

Almost surely, 2^{21005676408025} is an apocalyptic number.

21005676408025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21005676408025 is the 4583195-th square number.

21005676408025 is the 2291598-th centered octagonal number.

It is an amenable number.

21005676408025 is a deficient number, since it is larger than the sum of its proper divisors (5909603746148).

21005676408025 is an frugal number, since it uses more digits than its factorization.

21005676408025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59210 (or 29605 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 46.

The spelling of 21005676408025 in words is "twenty-one trillion, five billion, six hundred seventy-six million, four hundred eight thousand, twenty-five".