665078640 has 80 divisors (see below), whose sum is σ = 2064228000. Its totient is φ = 177140736.

The previous prime is 665078633. The next prime is 665078653. The reversal of 665078640 is 46870566.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a junction number, because it is equal to n+sod(n) for n = 665078592 and 665078601.

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, 370866 + ... + 372654.

It is an arithmetic number, because the mean of its divisors is an integer number (25802850).

Almost surely, 2^665078640 is an apocalyptic number.

665078640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665078640 is an abundant number, since it is smaller than the sum of its proper divisors (1399149360).

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

665078640 is a wasteful number, since it uses less digits than its factorization.

665078640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3354 (or 3348 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The square root of 665078640 is about 25789.1186355796. The cubic root of 665078640 is about 872.8862787145.

The spelling of 665078640 in words is "six hundred sixty-five million, seventy-eight thousand, six hundred forty".