665957640 has 128 divisors (see below), whose sum is σ = 2106259200. Its totient is φ = 168115200.

The previous prime is 665957639. The next prime is 665957659. The reversal of 665957640 is 46759566.

It is a self number, because there is not a number n which added to its sum of digits gives 665957640.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 277566 + ... + 279954.

It is an arithmetic number, because the mean of its divisors is an integer number (16455150).

Almost surely, 2^665957640 is an apocalyptic number.

665957640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665957640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1053129600).

665957640 is an abundant number, since it is smaller than the sum of its proper divisors (1440301560).

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

665957640 is a wasteful number, since it uses less digits than its factorization.

665957640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2527 (or 2523 counting only the distinct ones).

The product of its (nonzero) digits is 1360800, while the sum is 48.

The square root of 665957640 is about 25806.1550797479. The cubic root of 665957640 is about 873.2706589576.

The spelling of 665957640 in words is "six hundred sixty-five million, nine hundred fifty-seven thousand, six hundred forty".