189181989 has 12 divisors (see below), whose sum is σ = 275969772. Its totient is φ = 124872000.

The previous prime is 189181987. The next prime is 189181991. The reversal of 189181989 is 989181981.

It is an interprime number because it is at equal distance from previous prime (189181987) and next prime (189181991).

It can be written as a sum of positive squares in 2 ways, for example, as 101909025 + 87272964 = 10095^2 + 9342^2 .

It is not a de Polignac number, because 189181989 - 2¹ = 189181987 is a prime.

It is a super-2 number, since 2×189181989² = 71579649923992242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189181987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 103152 + ... + 104969.

It is an arithmetic number, because the mean of its divisors is an integer number (22997481).

Almost surely, 2^189181989 is an apocalyptic number.

It is an amenable number.

189181989 is a deficient number, since it is larger than the sum of its proper divisors (86787783).

189181989 is a wasteful number, since it uses less digits than its factorization.

189181989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208228 (or 208225 counting only the distinct ones).

The product of its digits is 373248, while the sum is 54.

The square root of 189181989 is about 13754.3443682351. The cubic root of 189181989 is about 574.0634927964.

The spelling of 189181989 in words is "one hundred eighty-nine million, one hundred eighty-one thousand, nine hundred eighty-nine".