66628515625 has 81 divisors (see below), whose sum is σ = 98553172197. Its totient is φ = 44913750000.

The previous prime is 66628515557. The next prime is 66628515649. The reversal of 66628515625 is 52651582666.

The square root of 66628515625 is 258125.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 47371957801 + 19256557824 = 217651^2 + 138768^2 .

It is not a de Polignac number, because 66628515625 - 2¹³ = 66628507433 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 1129296846 + ... + 1129296904.

Almost surely, 2^66628515625 is an apocalyptic number.

66628515625 is the 258125-th square number.

66628515625 is the 129063-rd centered octagonal number.

It is an amenable number.

66628515625 is a deficient number, since it is larger than the sum of its proper divisors (31924656572).

66628515625 is an frugal number, since it uses more digits than its factorization.

66628515625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172 (or 71 counting only the distinct ones).

The product of its digits is 5184000, while the sum is 52.

The spelling of 66628515625 in words is "sixty-six billion, six hundred twenty-eight million, five hundred fifteen thousand, six hundred twenty-five".