661959181 has 8 divisors (see below), whose sum is σ = 713444480. Its totient is φ = 610554672.

The previous prime is 661959169. The next prime is 661959217. The reversal of 661959181 is 181959166.

It is a happy number.

661959181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 661959181 - 2⁵ = 661959149 is a prime.

It is a super-2 number, since 2×661959181² = 876379914620381522, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661959101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2601 + ... + 36478.

It is an arithmetic number, because the mean of its divisors is an integer number (89180560).

Almost surely, 2^661959181 is an apocalyptic number.

It is an amenable number.

661959181 is a deficient number, since it is larger than the sum of its proper divisors (51485299).

661959181 is a wasteful number, since it uses less digits than its factorization.

661959181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40395.

The product of its digits is 116640, while the sum is 46.

The square root of 661959181 is about 25728.5674105652. The cubic root of 661959181 is about 871.5194221747.

The spelling of 661959181 in words is "six hundred sixty-one million, nine hundred fifty-nine thousand, one hundred eighty-one".