661456980 has 36 divisors (see below), whose sum is σ = 2006420052. Its totient is φ = 176388480.

The previous prime is 661456933. The next prime is 661457053. The reversal of 661456980 is 89654166.

661456980 is a `hidden beast` number, since 6 + 6 + 1 + 4 + 569 + 80 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 66292164 + 595164816 = 8142^2 + 24396^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1837201 + ... + 1837560.

Almost surely, 2^661456980 is an apocalyptic number.

661456980 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

661456980 is an abundant number, since it is smaller than the sum of its proper divisors (1344963072).

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

661456980 is a wasteful number, since it uses less digits than its factorization.

661456980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3674776 (or 3674771 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The square root of 661456980 is about 25718.8059598419. The cubic root of 661456980 is about 871.2989711926.

The spelling of 661456980 in words is "six hundred sixty-one million, four hundred fifty-six thousand, nine hundred eighty".