638320225 has 27 divisors (see below), whose sum is σ = 822921939. Its totient is φ = 491151600.

The previous prime is 638320223. The next prime is 638320261. The reversal of 638320225 is 522023836.

The square root of 638320225 is 25265.

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., 229795281 + 408524944 = 15159^2 + 20212^2 .

It is not a de Polignac number, because 638320225 - 2¹ = 638320223 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is not an unprimeable number, because it can be changed into a prime (638320223) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3915994 + ... + 3916156.

Almost surely, 2^638320225 is an apocalyptic number.

638320225 is the 25265-th square number.

638320225 is the 12633-rd centered octagonal number.

It is an amenable number.

638320225 is a deficient number, since it is larger than the sum of its proper divisors (184601714).

638320225 is an equidigital number, since it uses as much as digits as its factorization.

638320225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398 (or 199 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 31.

The cubic root of 638320225 is about 861.0192642780.

The spelling of 638320225 in words is "six hundred thirty-eight million, three hundred twenty thousand, two hundred twenty-five".