181199661 has 16 divisors (see below), whose sum is σ = 243629568. Its totient is φ = 119790000.

The previous prime is 181199659. The next prime is 181199671. The reversal of 181199661 is 166991181.

It is a happy number.

It is not a de Polignac number, because 181199661 - 2¹ = 181199659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181199621) 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, 248880 + ... + 249606.

It is an arithmetic number, because the mean of its divisors is an integer number (15226848).

Almost surely, 2^181199661 is an apocalyptic number.

It is an amenable number.

181199661 is a deficient number, since it is larger than the sum of its proper divisors (62429907).

181199661 is a wasteful number, since it uses less digits than its factorization.

181199661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1312.

The product of its digits is 23328, while the sum is 42.

The square root of 181199661 is about 13461.0423444843. The cubic root of 181199661 is about 565.8732011696.

The spelling of 181199661 in words is "one hundred eighty-one million, one hundred ninety-nine thousand, six hundred sixty-one".