189889981 has 2 divisors, whose sum is σ = 189889982. Its totient is φ = 189889980.

The previous prime is 189889963. The next prime is 189890023. The reversal of 189889981 is 189988981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 157502500 + 32387481 = 12550^2 + 5691^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-189889981 is a prime.

It is a super-2 number, since 2×189889981² = 72116409768360722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (189889481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94944990 + 94944991.

It is an arithmetic number, because the mean of its divisors is an integer number (94944991).

Almost surely, 2^189889981 is an apocalyptic number.

It is an amenable number.

189889981 is a deficient number, since it is larger than the sum of its proper divisors (1).

189889981 is an equidigital number, since it uses as much as digits as its factorization.

189889981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2985984, while the sum is 61.

The square root of 189889981 is about 13780.0573656281. The cubic root of 189889981 is about 574.7787236792.

The spelling of 189889981 in words is "one hundred eighty-nine million, eight hundred eighty-nine thousand, nine hundred eighty-one".