6661173855625 has 15 divisors (see below), whose sum is σ = 8323883478867. Its totient is φ = 5328887466000.

The previous prime is 6661173855619. The next prime is 6661173855649. The reversal of 6661173855625 is 5265583711666.

The square root of 6661173855625 is 2580925.

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

It can be written as a sum of positive squares in 7 ways, for example, as 875397883129 + 5785775972496 = 935627^2 + 2405364^2 .

It is not a de Polignac number, because 6661173855625 - 2²¹ = 6661171758473 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 64471507 + ... + 64574743.

Almost surely, 2^{6661173855625} is an apocalyptic number.

6661173855625 is the 2580925-th square number.

6661173855625 is the 1290463-rd centered octagonal number.

It is an amenable number.

6661173855625 is a deficient number, since it is larger than the sum of its proper divisors (1662709623242).

6661173855625 is an frugal number, since it uses more digits than its factorization.

6661173855625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206494 (or 103242 counting only the distinct ones).

The product of its digits is 54432000, while the sum is 61.

The spelling of 6661173855625 in words is "six trillion, six hundred sixty-one billion, one hundred seventy-three million, eight hundred fifty-five thousand, six hundred twenty-five".