665657118720 has 520 divisors, whose sum is σ = 2603212508160. Its totient is φ = 161366999040.

The previous prime is 665657118677. The next prime is 665657118839. The reversal of 665657118720 is 27811756566.

It is a happy number.

665657118720 is a `hidden beast` number, since 6 + 6 + 56 + 571 + 18 + 7 + 2 + 0 = 666.

It is a super-2 number, since 2×665657118720² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 18229441 + ... + 18265919.

Almost surely, 2^665657118720 is an apocalyptic number.

665657118720 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 665657118720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1301606254080).

665657118720 is an abundant number, since it is smaller than the sum of its proper divisors (1937555389440).

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

665657118720 is a wasteful number, since it uses less digits than its factorization.

665657118720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36531 (or 36500 counting only the distinct ones).

The product of its (nonzero) digits is 4233600, while the sum is 54.

The spelling of 665657118720 in words is "six hundred sixty-five billion, six hundred fifty-seven million, one hundred eighteen thousand, seven hundred twenty".