189727981 has 2 divisors, whose sum is σ = 189727982. Its totient is φ = 189727980.

The previous prime is 189727963. The next prime is 189727991.

189727981 is nontrivially palindromic in base 10.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 150552900 + 39175081 = 12270^2 + 6259^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 189727981 - 2⁹ = 189727469 is a prime.

It is a super-2 number, since 2×189727981² = 71993413548672722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (189727931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94863990 + 94863991.

It is an arithmetic number, because the mean of its divisors is an integer number (94863991).

Almost surely, 2^189727981 is an apocalyptic number.

It is an amenable number.

189727981 is a deficient number, since it is larger than the sum of its proper divisors (1).

189727981 is an equidigital number, since it uses as much as digits as its factorization.

189727981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 508032, while the sum is 52.

The square root of 189727981 is about 13774.1780517024. The cubic root of 189727981 is about 574.6152243647.

The spelling of 189727981 in words is "one hundred eighty-nine million, seven hundred twenty-seven thousand, nine hundred eighty-one".