665661660500 has 48 divisors (see below), whose sum is σ = 1470140053200. Its totient is φ = 263272908800.

The previous prime is 665661660497. The next prime is 665661660509. The reversal of 665661660500 is 5066166566.

It can be written as a sum of positive squares in 8 ways, for example, as 503597445316 + 162064215184 = 709646^2 + 402572^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665661660509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7434845 + ... + 7523844.

It is an arithmetic number, because the mean of its divisors is an integer number (30627917775).

Almost surely, 2^665661660500 is an apocalyptic number.

It is an amenable number.

665661660500 is an abundant number, since it is smaller than the sum of its proper divisors (804478392700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665661660500 is a wasteful number, since it uses less digits than its factorization.

665661660500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14958797 (or 14958785 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 47.

The spelling of 665661660500 in words is "six hundred sixty-five billion, six hundred sixty-one million, six hundred sixty thousand, five hundred".