663864339769225 has 27 divisors (see below), whose sum is σ = 957591740282247. Its totient is φ = 455220643182480.

The previous prime is 663864339769207. The next prime is 663864339769231. The reversal of 663864339769225 is 522967933468366.

The square root of 663864339769225 is 25765565.

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., 238991162316921 + 424873177452304 = 15459339^2 + 20612452^2 .

It is not a de Polignac number, because 663864339769225 - 2⁷ = 663864339769097 is a prime.

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, 901426696 + ... + 902162854.

Almost surely, 2^{663864339769225} is an apocalyptic number.

663864339769225 is the 25765565-th square number.

663864339769225 is the 12882783-rd centered octagonal number.

It is an amenable number.

663864339769225 is a deficient number, since it is larger than the sum of its proper divisors (293727400513022).

663864339769225 is an frugal number, since it uses more digits than its factorization.

663864339769225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1472342 (or 736171 counting only the distinct ones).

The product of its digits is 12697896960, while the sum is 79.

The spelling of 663864339769225 in words is "six hundred sixty-three trillion, eight hundred sixty-four billion, three hundred thirty-nine million, seven hundred sixty-nine thousand, two hundred twenty-five".