115921 has 8 divisors (see below), whose sum is σ = 128744. Its totient is φ = 103680.

The previous prime is 115903. The next prime is 115931. The reversal of 115921 is 129511.

115921 is a nontrivial binomial coefficient, being equal to C(482, 2).

It can be written as a sum of positive squares in 4 ways, for example, as 32400 + 83521 = 180^2 + 289^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 2-Lehmer number, since φ(115921) divides (115921-1)².

It is a cyclic number.

It is a Carmichael number.

It is not a de Polignac number, because 115921 - 2⁷ = 115793 is a prime.

It is a deceptive number, since it divides R₁₁₅₉₂₀.

It is a Duffinian number.

115921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (115901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 361 + ... + 601.

It is an arithmetic number, because the mean of its divisors is an integer number (16093).

It is a Poulet number, since it divides 2¹¹⁵⁹²⁰-1.

2¹¹⁵⁹²¹ is an apocalyptic number.

115921 is the 481-st triangular number and also the 241-st hexagonal number.

115921 is the 161-st centered nonagonal number.

It is an amenable number.

115921 is a deficient number, since it is larger than the sum of its proper divisors (12823).

115921 is a wasteful number, since it uses less digits than its factorization.

115921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291.

The product of its digits is 90, while the sum is 19.

The square root of 115921 is about 340.4717315725. The cubic root of 115921 is about 48.7589157482.

The spelling of 115921 in words is "one hundred fifteen thousand, nine hundred twenty-one".