665679976566 has 128 divisors (see below), whose sum is σ = 1505922416640. Its totient is φ = 194398704000.

The previous prime is 665679976531. The next prime is 665679976573.

665679976566 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 665679976491 and 665679976500.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 135325855 + ... + 135330773.

It is an arithmetic number, because the mean of its divisors is an integer number (11765018880).

Almost surely, 2^665679976566 is an apocalyptic number.

665679976566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 665679976566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (752961208320).

665679976566 is an abundant number, since it is smaller than the sum of its proper divisors (840242440074).

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

665679976566 is a wasteful number, since it uses less digits than its factorization.

665679976566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5490.

The product of its digits is 4629441600, while the sum is 78.

The spelling of 665679976566 in words is "six hundred sixty-five billion, six hundred seventy-nine million, nine hundred seventy-six thousand, five hundred sixty-six".