661330980 has 60 divisors (see below), whose sum is σ = 2074624860. Its totient is φ = 176354496.

The previous prime is 661330963. The next prime is 661330981. The reversal of 661330980 is 89033166.

It is a happy number.

661330980 is a `hidden beast` number, since 6 + 613 + 30 + 9 + 8 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 305480484 + 355850496 = 17478^2 + 18864^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661330981) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 202495 + ... + 205734.

It is an arithmetic number, because the mean of its divisors is an integer number (34577081).

Almost surely, 2^661330980 is an apocalyptic number.

661330980 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661330980 is an abundant number, since it is smaller than the sum of its proper divisors (1413293880).

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

661330980 is a wasteful number, since it uses less digits than its factorization.

661330980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408250 (or 408239 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 661330980 is about 25716.3562737803. The cubic root of 661330980 is about 871.2436435118.

The spelling of 661330980 in words is "six hundred sixty-one million, three hundred thirty thousand, nine hundred eighty".