664225 has 9 divisors (see below), whose sum is σ = 828723. Its totient is φ = 528120.

The previous prime is 664211. The next prime is 664243. The reversal of 664225 is 522466.

The square root of 664225 is 815.

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., 239121 + 425104 = 489^2 + 652^2 .

It is not a de Polignac number, because 664225 - 2⁵ = 664193 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

664225 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 664225.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 3994 + ... + 4156.

2⁶⁶⁴²²⁵ is an apocalyptic number.

664225 is the 815-th square number.

664225 is the 408-th centered octagonal number.

It is an amenable number.

664225 is a deficient number, since it is larger than the sum of its proper divisors (164498).

664225 is an equidigital number, since it uses as much as digits as its factorization.

664225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336 (or 168 counting only the distinct ones).

The product of its digits is 2880, while the sum is 25.

The cubic root of 664225 is about 87.2512663916.

Multiplying 664225 by its sum of digits (25), we get a square (16605625 = 4075²).

664225 divided by its sum of digits (25) gives a square (26569 = 163²).

The spelling of 664225 in words is "six hundred sixty-four thousand, two hundred twenty-five".