664668720 has 320 divisors, whose sum is σ = 2532695040. Its totient is φ = 159363072.

The previous prime is 664668713. The next prime is 664668721. The reversal of 664668720 is 27866466.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (664668721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 844167 + ... + 844953.

It is an arithmetic number, because the mean of its divisors is an integer number (7914672).

Almost surely, 2^664668720 is an apocalyptic number.

664668720 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 664668720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1266347520).

664668720 is an abundant number, since it is smaller than the sum of its proper divisors (1868026320).

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

664668720 is a wasteful number, since it uses less digits than its factorization.

664668720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849 (or 837 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 45.

The square root of 664668720 is about 25781.1698726028. The cubic root of 664668720 is about 872.7069079055.

The spelling of 664668720 in words is "six hundred sixty-four million, six hundred sixty-eight thousand, seven hundred twenty".