115978921 has 4 divisors (see below), whose sum is σ = 116021700. Its totient is φ = 115936144.

The previous prime is 115978897. The next prime is 115978937. The reversal of 115978921 is 129879511.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 84842521 + 31136400 = 9211^2 + 5580^2 .

It is a cyclic number.

It is not a de Polignac number, because 115978921 - 2¹⁵ = 115946153 is a prime.

It is a super-2 number, since 2×115978921² = 26902220232648482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (115978021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17026 + ... + 22843.

It is an arithmetic number, because the mean of its divisors is an integer number (29005425).

Almost surely, 2^115978921 is an apocalyptic number.

It is an amenable number.

115978921 is a deficient number, since it is larger than the sum of its proper divisors (42779).

115978921 is an equidigital number, since it uses as much as digits as its factorization.

115978921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42778.

The product of its digits is 45360, while the sum is 43.

The square root of 115978921 is about 10769.3510018014. The cubic root of 115978921 is about 487.6703534382.

The spelling of 115978921 in words is "one hundred fifteen million, nine hundred seventy-eight thousand, nine hundred twenty-one".