665727727566 has 96 divisors (see below), whose sum is σ = 1511559189504. Its totient is φ = 195118387200.

The previous prime is 665727727543. The next prime is 665727727583.

665727727566 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a junction number, because it is equal to n+sod(n) for n = 665727727497 and 665727727506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 45612366 + ... + 45626958.

It is an arithmetic number, because the mean of its divisors is an integer number (15745408224).

Almost surely, 2^665727727566 is an apocalyptic number.

665727727566 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 665727727566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (755779594752).

665727727566 is an abundant number, since it is smaller than the sum of its proper divisors (845831461938).

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

665727727566 is a wasteful number, since it uses less digits than its factorization.

665727727566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16678 (or 16667 counting only the distinct ones).

The product of its digits is 311169600, while the sum is 66.

The spelling of 665727727566 in words is "six hundred sixty-five billion, seven hundred twenty-seven million, seven hundred twenty-seven thousand, five hundred sixty-six".