189981881 has 2 divisors, whose sum is σ = 189981882. Its totient is φ = 189981880.

The previous prime is 189981809. The next prime is 189981889. The reversal of 189981881 is 188189981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 176358400 + 13623481 = 13280^2 + 3691^2 .

It is a cyclic number.

It is not a de Polignac number, because 189981881 - 2²⁶ = 122873017 is a prime.

It is a super-2 number, since 2×189981881² = 72186230216596322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (189981889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94990940 + 94990941.

It is an arithmetic number, because the mean of its divisors is an integer number (94990941).

Almost surely, 2^189981881 is an apocalyptic number.

It is an amenable number.

189981881 is a deficient number, since it is larger than the sum of its proper divisors (1).

189981881 is an equidigital number, since it uses as much as digits as its factorization.

189981881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 331776, while the sum is 53.

The square root of 189981881 is about 13783.3914912114. The cubic root of 189981881 is about 574.8714328809.

It can be divided in two parts, 18 and 9981881, that added together give a palindrome (9981899).

The spelling of 189981881 in words is "one hundred eighty-nine million, nine hundred eighty-one thousand, eight hundred eighty-one".