66609581725 has 12 divisors (see below), whose sum is σ = 83326821876. Its totient is φ = 52816090880.

The previous prime is 66609581693. The next prime is 66609581729. The reversal of 66609581725 is 52718590666.

It can be written as a sum of positive squares in 6 ways, for example, as 5668734681 + 60940847044 = 75291^2 + 246862^2 .

It is not a de Polignac number, because 66609581725 - 2⁵ = 66609581693 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66609581729) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11786482 + ... + 11792131.

It is an arithmetic number, because the mean of its divisors is an integer number (6943901823).

Almost surely, 2^66609581725 is an apocalyptic number.

It is an amenable number.

66609581725 is a deficient number, since it is larger than the sum of its proper divisors (16717240151).

66609581725 is a wasteful number, since it uses less digits than its factorization.

66609581725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23578736 (or 23578731 counting only the distinct ones).

The product of its (nonzero) digits is 5443200, while the sum is 55.

The spelling of 66609581725 in words is "sixty-six billion, six hundred nine million, five hundred eighty-one thousand, seven hundred twenty-five".