665995680 has 144 divisors (see below), whose sum is σ = 2597422464. Its totient is φ = 152225280.

The previous prime is 665995679. The next prime is 665995699. The reversal of 665995680 is 86599566.

It is a tau number, because it is divible by the number of its divisors (144).

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 23 ways as a sum of consecutive naturals, for example, 22956 + ... + 43115.

It is an arithmetic number, because the mean of its divisors is an integer number (18037656).

Almost surely, 2^665995680 is an apocalyptic number.

665995680 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665995680 is an abundant number, since it is smaller than the sum of its proper divisors (1931426784).

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

665995680 is a wasteful number, since it uses less digits than its factorization.

665995680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66099 (or 66088 counting only the distinct ones).

The product of its (nonzero) digits is 3499200, while the sum is 54.

The square root of 665995680 is about 25806.8921026923. The cubic root of 665995680 is about 873.2872859327.

The spelling of 665995680 in words is "six hundred sixty-five million, nine hundred ninety-five thousand, six hundred eighty".