21523985966025 has 27 divisors (see below), whose sum is σ = 38551975064629. Its totient is φ = 11479422066720.

The previous prime is 21523985966023. The next prime is 21523985966053. The reversal of 21523985966025 is 52066958932512.

The square root of 21523985966025 is 4639395.

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

21523985966025 is a `hidden beast` number, since 2 + 1 + 5 + 2 + 39 + 8 + 596 + 6 + 0 + 2 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 5030380608201 + 16493605357824 = 2242851^2 + 4061232^2 .

It is not a de Polignac number, because 21523985966025 - 2¹ = 21523985966023 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21523985966023) 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, 69436279 + ... + 69745571.

Almost surely, 2^{21523985966025} is an apocalyptic number.

21523985966025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21523985966025 is the 4639395-th square number.

21523985966025 is the 2319698-th centered octagonal number.

It is an amenable number.

21523985966025 is a deficient number, since it is larger than the sum of its proper divisors (17027989098604).

21523985966025 is an frugal number, since it uses more digits than its factorization.

21523985966025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618602 (or 309301 counting only the distinct ones).

The product of its (nonzero) digits is 69984000, while the sum is 63.

The spelling of 21523985966025 in words is "twenty-one trillion, five hundred twenty-three billion, nine hundred eighty-five million, nine hundred sixty-six thousand, twenty-five".