661165055320 has 128 divisors (see below), whose sum is σ = 1877043248640. Its totient is φ = 203594480640.

The previous prime is 661165055297. The next prime is 661165055323. The reversal of 661165055320 is 23550561166.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661165055323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1037517 + ... + 1548796.

It is an arithmetic number, because the mean of its divisors is an integer number (14664400380).

Almost surely, 2^661165055320 is an apocalyptic number.

It is an amenable number.

661165055320 is an abundant number, since it is smaller than the sum of its proper divisors (1215878193320).

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

661165055320 is a wasteful number, since it uses less digits than its factorization.

661165055320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2586425 (or 2586421 counting only the distinct ones).

The product of its (nonzero) digits is 162000, while the sum is 40.

The spelling of 661165055320 in words is "six hundred sixty-one billion, one hundred sixty-five million, fifty-five thousand, three hundred twenty".