665640660 has 24 divisors (see below), whose sum is σ = 1863794016. Its totient is φ = 177504160.

The previous prime is 665640659. The next prime is 665640671. The reversal of 665640660 is 66046566.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5546946 + ... + 5547065.

It is an arithmetic number, because the mean of its divisors is an integer number (77658084).

Almost surely, 2^665640660 is an apocalyptic number.

665640660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665640660 is an abundant number, since it is smaller than the sum of its proper divisors (1198153356).

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

665640660 is a wasteful number, since it uses less digits than its factorization.

665640660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11094023 (or 11094021 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 39.

The square root of 665640660 is about 25800.0127906945. The cubic root of 665640660 is about 873.1320849469.

The spelling of 665640660 in words is "six hundred sixty-five million, six hundred forty thousand, six hundred sixty".