661887788166 has 48 divisors (see below), whose sum is σ = 1564819905168. Its totient is φ = 200526177600.

The previous prime is 661887788119. The next prime is 661887788171.

661887788166 is nontrivially palindromic in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 661887788094 and 661887788103.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 490476 + ... + 1250736.

It is an arithmetic number, because the mean of its divisors is an integer number (32600414691).

Almost surely, 2^661887788166 is an apocalyptic number.

661887788166 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

661887788166 is an abundant number, since it is smaller than the sum of its proper divisors (902932117002).

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

661887788166 is a wasteful number, since it uses less digits than its factorization.

661887788166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 764677 (or 764674 counting only the distinct ones).

The product of its digits is 260112384, while the sum is 72.

The spelling of 661887788166 in words is "six hundred sixty-one billion, eight hundred eighty-seven million, seven hundred eighty-eight thousand, one hundred sixty-six".