666640980 has 72 divisors (see below), whose sum is σ = 2091889800. Its totient is φ = 171639552.

The previous prime is 666640967. The next prime is 666641023. The reversal of 666640980 is 89046666.

It can be written as a sum of positive squares in 4 ways, for example, as 50211396 + 616429584 = 7086^2 + 24828^2 .

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 polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 58635 + ... + 69074.

It is an arithmetic number, because the mean of its divisors is an integer number (29054025).

Almost surely, 2^666640980 is an apocalyptic number.

666640980 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

666640980 is an abundant number, since it is smaller than the sum of its proper divisors (1425248820).

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

666640980 is a wasteful number, since it uses less digits than its factorization.

666640980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127753 (or 127748 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The square root of 666640980 is about 25819.3915497635. The cubic root of 666640980 is about 873.5692449071.

The spelling of 666640980 in words is "six hundred sixty-six million, six hundred forty thousand, nine hundred eighty".