660640640 has 192 divisors, whose sum is σ = 1831410000. Its totient is φ = 227082240.

The previous prime is 660640637. The next prime is 660640709. The reversal of 660640640 is 46046066.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 660640597 and 660640606.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1471136 + ... + 1471584.

Almost surely, 2^660640640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 660640640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (915705000).

660640640 is an abundant number, since it is smaller than the sum of its proper divisors (1170769360).

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

660640640 is a wasteful number, since it uses less digits than its factorization.

660640640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509 (or 486 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 32.

The square root of 660640640 is about 25702.9305722130. The cubic root of 660640640 is about 870.9403845005.

The spelling of 660640640 in words is "six hundred sixty million, six hundred forty thousand, six hundred forty".