181999961 has 16 divisors (see below), whose sum is σ = 214263168. Its totient is φ = 152409600.

The previous prime is 181999957. The next prime is 181999973. The reversal of 181999961 is 169999181.

181999961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 181999961 - 2² = 181999957 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181999901) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 89225 + ... + 91241.

It is an arithmetic number, because the mean of its divisors is an integer number (13391448).

Almost surely, 2^181999961 is an apocalyptic number.

181999961 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

181999961 is a deficient number, since it is larger than the sum of its proper divisors (32263207).

181999961 is a wasteful number, since it uses less digits than its factorization.

181999961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2672.

The product of its digits is 314928, while the sum is 53.

The square root of 181999961 is about 13490.7361177958. The cubic root of 181999961 is about 566.7050703308.

The spelling of 181999961 in words is "one hundred eighty-one million, nine hundred ninety-nine thousand, nine hundred sixty-one".