661864424468166 has 24 divisors (see below), whose sum is σ = 1469016161626104. Its totient is φ = 215240463241440.

The previous prime is 661864424468123. The next prime is 661864424468213.

661864424468166 is a `hidden beast` number, since 6 + 6 + 1 + 8 + 6 + 4 + 42 + 446 + 81 + 66 = 666.

661864424468166 is nontrivially palindromic in base 10.

It is a hoax number, since the sum of its digits (72) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 661864424468094 and 661864424468103.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 448417631016 + ... + 448417632491.

It is an arithmetic number, because the mean of its divisors is an integer number (61209006734421).

Almost surely, 2^{661864424468166} is an apocalyptic number.

661864424468166 is an abundant number, since it is smaller than the sum of its proper divisors (807151737157938).

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

661864424468166 is a wasteful number, since it uses less digits than its factorization.

661864424468166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 896835263556 (or 896835263553 counting only the distinct ones).

The product of its digits is 1528823808, while the sum is 72.

The spelling of 661864424468166 in words is "six hundred sixty-one trillion, eight hundred sixty-four billion, four hundred twenty-four million, four hundred sixty-eight thousand, one hundred sixty-six".