115221989 has 2 divisors, whose sum is σ = 115221990. Its totient is φ = 115221988.

The previous prime is 115221961. The next prime is 115221991. The reversal of 115221989 is 989122511.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 108513889 + 6708100 = 10417^2 + 2590^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-115221989 is a prime.

It is a super-2 number, since 2×115221989² = 26552213498232242, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 115221991, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is equal to p_6584645 and since 115221989 and 6584645 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (115221949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 57610994 + 57610995.

It is an arithmetic number, because the mean of its divisors is an integer number (57610995).

Almost surely, 2^115221989 is an apocalyptic number.

It is an amenable number.

115221989 is a deficient number, since it is larger than the sum of its proper divisors (1).

115221989 is an equidigital number, since it uses as much as digits as its factorization.

115221989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 38.

The square root of 115221989 is about 10734.1505951799. The cubic root of 115221989 is about 486.6071163661.

The spelling of 115221989 in words is "one hundred fifteen million, two hundred twenty-one thousand, nine hundred eighty-nine".