665423590225 has 9 divisors (see below), whose sum is σ = 825130309467. Its totient is φ = 532335609240.

The previous prime is 665423590207. The next prime is 665423590309. The reversal of 665423590225 is 522095324566.

The square root of 665423590225 is 815735.

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., 239552492481 + 425871097744 = 489441^2 + 652588^2 .

It is not a de Polignac number, because 665423590225 - 2⁹ = 665423589713 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3997102 + ... + 4160248.

Almost surely, 2^665423590225 is an apocalyptic number.

665423590225 is the 815735-th square number.

665423590225 is the 407868-th centered octagonal number.

It is an amenable number.

665423590225 is a deficient number, since it is larger than the sum of its proper divisors (159706719242).

665423590225 is an frugal number, since it uses more digits than its factorization.

665423590225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 326304 (or 163152 counting only the distinct ones).

The product of its (nonzero) digits is 3888000, while the sum is 49.

Multiplying 665423590225 by its sum of digits (49), we get a square (32605755921025 = 5710145²).

The spelling of 665423590225 in words is "six hundred sixty-five billion, four hundred twenty-three million, five hundred ninety thousand, two hundred twenty-five".