661804634085760 has 128 divisors (see below), whose sum is σ = 1728896714979840. Its totient is φ = 240246252533760.

The previous prime is 661804634085689. The next prime is 661804634085769. The reversal of 661804634085760 is 67580436408166.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a junction number, because it is equal to n+sod(n) for n = 661804634085692 and 661804634085701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661804634085769) 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, 75941064 + ... + 84206023.

It is an arithmetic number, because the mean of its divisors is an integer number (13507005585780).

Almost surely, 2^{661804634085760} is an apocalyptic number.

It is an amenable number.

661804634085760 is an abundant number, since it is smaller than the sum of its proper divisors (1067092080894080).

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

661804634085760 is a wasteful number, since it uses less digits than its factorization.

661804634085760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160147704 (or 160147692 counting only the distinct ones).

The product of its (nonzero) digits is 139345920, while the sum is 64.

The spelling of 661804634085760 in words is "six hundred sixty-one trillion, eight hundred four billion, six hundred thirty-four million, eighty-five thousand, seven hundred sixty".