665547745566 has 64 divisors (see below), whose sum is σ = 1529605969920. Its totient is φ = 190931931360.

The previous prime is 665547745561. The next prime is 665547745619.

665547745566 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 = 665547745497 and 665547745506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665547745561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1603495 + ... + 1975421.

It is an arithmetic number, because the mean of its divisors is an integer number (23900093280).

Almost surely, 2^665547745566 is an apocalyptic number.

665547745566 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 665547745566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (764802984960).

665547745566 is an abundant number, since it is smaller than the sum of its proper divisors (864058224354).

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

665547745566 is a wasteful number, since it uses less digits than its factorization.

665547745566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373389.

The product of its digits is 635040000, while the sum is 66.

The spelling of 665547745566 in words is "six hundred sixty-five billion, five hundred forty-seven million, seven hundred forty-five thousand, five hundred sixty-six".