665390625 has 64 divisors (see below), whose sum is σ = 1181246976. Its totient is φ = 332000000.

The previous prime is 665390617. The next prime is 665390639. The reversal of 665390625 is 526093566.

It is not a de Polignac number, because 665390625 - 2³ = 665390617 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3984292 + ... + 3984458.

It is an arithmetic number, because the mean of its divisors is an integer number (18456984).

Almost surely, 2^665390625 is an apocalyptic number.

It is an amenable number.

665390625 is a deficient number, since it is larger than the sum of its proper divisors (515856351).

665390625 is an frugal number, since it uses more digits than its factorization.

665390625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222 (or 192 counting only the distinct ones).

The product of its (nonzero) digits is 291600, while the sum is 42.

The square root of 665390625 is about 25795.1666984340. The cubic root of 665390625 is about 873.0227462127.

The spelling of 665390625 in words is "six hundred sixty-five million, three hundred ninety thousand, six hundred twenty-five".