665633640 has 192 divisors, whose sum is σ = 2459937600. Its totient is φ = 143173632.

The previous prime is 665633629. The next prime is 665633651. The reversal of 665633640 is 46336566.

It is a happy number.

665633640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (665633629) and next prime (665633651).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 96631 + ... + 103289.

It is an arithmetic number, because the mean of its divisors is an integer number (12812175).

Almost surely, 2^665633640 is an apocalyptic number.

665633640 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 665633640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1229968800).

665633640 is an abundant number, since it is smaller than the sum of its proper divisors (1794303960).

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

665633640 is a wasteful number, since it uses less digits than its factorization.

665633640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6704 (or 6693 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 39.

The square root of 665633640 is about 25799.8767438916. The cubic root of 665633640 is about 873.1290155186.

The spelling of 665633640 in words is "six hundred sixty-five million, six hundred thirty-three thousand, six hundred forty".