21185261535025 has 27 divisors (see below), whose sum is σ = 30558891258219. Its totient is φ = 14526926015280.

The previous prime is 21185261534887. The next prime is 21185261535037. The reversal of 21185261535025 is 52053516258112.

The square root of 21185261535025 is 4602745.

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., 7626694152609 + 13558567382416 = 2761647^2 + 3682196^2 .

It is not a de Polignac number, because 21185261535025 - 2⁹ = 21185261534513 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, 161030322 + ... + 161161828.

Almost surely, 2^{21185261535025} is an apocalyptic number.

21185261535025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21185261535025 is the 4602745-th square number.

21185261535025 is the 2301373-rd centered octagonal number.

It is an amenable number.

21185261535025 is a deficient number, since it is larger than the sum of its proper divisors (9373629723194).

21185261535025 is an frugal number, since it uses more digits than its factorization.

21185261535025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263038 (or 131519 counting only the distinct ones).

The product of its (nonzero) digits is 720000, while the sum is 46.

The spelling of 21185261535025 in words is "twenty-one trillion, one hundred eighty-five billion, two hundred sixty-one million, five hundred thirty-five thousand, twenty-five".