661575575166 has 384 divisors, whose sum is σ = 1673265807360. Its totient is φ = 172206777600.

The previous prime is 661575575161. The next prime is 661575575191.

661575575166 is nontrivially palindromic in base 10.

661575575166 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661575575161) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1089910035 + ... + 1089910641.

It is an arithmetic number, because the mean of its divisors is an integer number (4357463040).

Almost surely, 2^661575575166 is an apocalyptic number.

661575575166 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 661575575166, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (836632903680).

661575575166 is an abundant number, since it is smaller than the sum of its proper divisors (1011690232194).

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

661575575166 is a wasteful number, since it uses less digits than its factorization.

661575575166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 772 (or 749 counting only the distinct ones).

The product of its digits is 39690000, while the sum is 60.

The spelling of 661575575166 in words is "six hundred sixty-one billion, five hundred seventy-five million, five hundred seventy-five thousand, one hundred sixty-six".