189959981 has 4 divisors (see below), whose sum is σ = 190448700. Its totient is φ = 189471264.

The previous prime is 189959969. The next prime is 189959983.

189959981 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 32959081 + 157000900 = 5741^2 + 12530^2 .

It is a cyclic number.

It is not a de Polignac number, because 189959981 - 2²⁶ = 122851117 is a prime.

It is a super-2 number, since 2×189959981² = 72169588763040722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 189959981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189959983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 243776 + ... + 244553.

It is an arithmetic number, because the mean of its divisors is an integer number (47612175).

Almost surely, 2^189959981 is an apocalyptic number.

It is an amenable number.

189959981 is a deficient number, since it is larger than the sum of its proper divisors (488719).

189959981 is an equidigital number, since it uses as much as digits as its factorization.

189959981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488718.

The product of its digits is 2099520, while the sum is 59.

The square root of 189959981 is about 13782.5970339410. The cubic root of 189959981 is about 574.8493427600.

The spelling of 189959981 in words is "one hundred eighty-nine million, nine hundred fifty-nine thousand, nine hundred eighty-one".