656399734225 has 27 divisors (see below), whose sum is σ = 841199560731. Its totient is φ = 508083217200.

The previous prime is 656399734181. The next prime is 656399734279. The reversal of 656399734225 is 522437993656.

The square root of 656399734225 is 810185.

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., 236303904321 + 420095829904 = 486111^2 + 648148^2 .

It is not a de Polignac number, because 656399734225 - 2¹⁵ = 656399701457 is a prime.

It is a super-2 number, since 2×656399734225² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 125576062 + ... + 125581288.

Almost surely, 2^656399734225 is an apocalyptic number.

656399734225 is the 810185-th square number.

656399734225 is the 405093-rd centered octagonal number.

It is an amenable number.

656399734225 is a deficient number, since it is larger than the sum of its proper divisors (184799826506).

656399734225 is an frugal number, since it uses more digits than its factorization.

656399734225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10526 (or 5263 counting only the distinct ones).

The product of its digits is 73483200, while the sum is 61.

The spelling of 656399734225 in words is "six hundred fifty-six billion, three hundred ninety-nine million, seven hundred thirty-four thousand, two hundred twenty-five".