661094181 has 24 divisors (see below), whose sum is σ = 1103004864. Its totient is φ = 377093760.

The previous prime is 661094177. The next prime is 661094191. The reversal of 661094181 is 181490166.

It is a happy number.

It is not a de Polignac number, because 661094181 - 2² = 661094177 is a prime.

It is a super-2 number, since 2×661094181² = 874091032304121522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661094191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 194721 + ... + 198086.

It is an arithmetic number, because the mean of its divisors is an integer number (45958536).

Almost surely, 2^661094181 is an apocalyptic number.

It is an amenable number.

661094181 is a deficient number, since it is larger than the sum of its proper divisors (441910683).

661094181 is a wasteful number, since it uses less digits than its factorization.

661094181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 392841 (or 392838 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 661094181 is about 25711.7518072962. The cubic root of 661094181 is about 871.1396440225.

The spelling of 661094181 in words is "six hundred sixty-one million, ninety-four thousand, one hundred eighty-one".