665445720 has 64 divisors (see below), whose sum is σ = 1998743040. Its totient is φ = 177238400.

The previous prime is 665445701. The next prime is 665445749. The reversal of 665445720 is 27544566.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 113665 + ... + 119375.

It is an arithmetic number, because the mean of its divisors is an integer number (31230360).

Almost surely, 2^665445720 is an apocalyptic number.

665445720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665445720 is an abundant number, since it is smaller than the sum of its proper divisors (1333297320).

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

665445720 is a wasteful number, since it uses less digits than its factorization.

665445720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6696 (or 6692 counting only the distinct ones).

The product of its (nonzero) digits is 201600, while the sum is 39.

The square root of 665445720 is about 25796.2346089502. The cubic root of 665445720 is about 873.0468412625.

The spelling of 665445720 in words is "six hundred sixty-five million, four hundred forty-five thousand, seven hundred twenty".