665898025 has 27 divisors (see below), whose sum is σ = 896373711. Its totient is φ = 490501440.

The previous prime is 665898019. The next prime is 665898067. The reversal of 665898025 is 520898566.

The square root of 665898025 is 25805.

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

It can be written as a sum of positive squares in 13 ways, for example, as 551921049 + 113976976 = 23493^2 + 10676^2 .

It is not a de Polignac number, because 665898025 - 2⁹ = 665897513 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 665898025.

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, 1677127 + ... + 1677523.

Almost surely, 2^665898025 is an apocalyptic number.

665898025 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

665898025 is the 25805-th square number.

665898025 is the 12903-rd centered octagonal number.

It is an amenable number.

665898025 is a deficient number, since it is larger than the sum of its proper divisors (230475686).

665898025 is an equidigital number, since it uses as much as digits as its factorization.

665898025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830 (or 415 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 49.

The cubic root of 665898025 is about 873.2446004514.

Multiplying 665898025 by its sum of digits (49), we get a square (32629003225 = 180635²).

The spelling of 665898025 in words is "six hundred sixty-five million, eight hundred ninety-eight thousand, twenty-five".