661958780 has 48 divisors (see below), whose sum is σ = 1590214080. Its totient is φ = 226741248.

The previous prime is 661958743. The next prime is 661958807. The reversal of 661958780 is 87859166.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 232244 + ... + 235076.

It is an arithmetic number, because the mean of its divisors is an integer number (33129460).

Almost surely, 2^661958780 is an apocalyptic number.

It is an amenable number.

661958780 is an abundant number, since it is smaller than the sum of its proper divisors (928255300).

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

661958780 is a wasteful number, since it uses less digits than its factorization.

661958780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4518 (or 4516 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 50.

The square root of 661958780 is about 25728.5596176700. The cubic root of 661958780 is about 871.5192461923.

The spelling of 661958780 in words is "six hundred sixty-one million, nine hundred fifty-eight thousand, seven hundred eighty".