665499667680 has 672 divisors, whose sum is σ = 2470198187520. Its totient is φ = 169032821760.

The previous prime is 665499667673. The next prime is 665499667691. The reversal of 665499667680 is 86766994566.

It is a happy number.

665499667680 is a `hidden beast` number, since 6 + 6 + 5 + 499 + 66 + 76 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 665499667599 and 665499667608.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 963096135 + ... + 963096825.

It is an arithmetic number, because the mean of its divisors is an integer number (3675890160).

Almost surely, 2^665499667680 is an apocalyptic number.

665499667680 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 665499667680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1235099093760).

665499667680 is an abundant number, since it is smaller than the sum of its proper divisors (1804698519840).

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

665499667680 is a wasteful number, since it uses less digits than its factorization.

665499667680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1106 (or 1083 counting only the distinct ones).

The product of its (nonzero) digits is 705438720, while the sum is 72.

The spelling of 665499667680 in words is "six hundred sixty-five billion, four hundred ninety-nine million, six hundred sixty-seven thousand, six hundred eighty".