189555981 has 16 divisors (see below), whose sum is σ = 256374720. Its totient is φ = 124561280.

The previous prime is 189555973. The next prime is 189555983.

It is a happy number.

189555981 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 189555981 - 2³ = 189555973 is a prime.

It is a super-2 number, since 2×189555981² = 71862939865744722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189555983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 200971 + ... + 201911.

It is an arithmetic number, because the mean of its divisors is an integer number (16023420).

Almost surely, 2^189555981 is an apocalyptic number.

It is an amenable number.

189555981 is a deficient number, since it is larger than the sum of its proper divisors (66818739).

189555981 is an equidigital number, since it uses as much as digits as its factorization.

189555981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1836.

The product of its digits is 648000, while the sum is 51.

The square root of 189555981 is about 13767.9330692737. The cubic root of 189555981 is about 574.4415306034.

The spelling of 189555981 in words is "one hundred eighty-nine million, five hundred fifty-five thousand, nine hundred eighty-one".