115721 has 4 divisors (see below), whose sum is σ = 117012. Its totient is φ = 114432.

The previous prime is 115693. The next prime is 115727. The reversal of 115721 is 127511.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127511 = 47 ⋅2713.

It can be written as a sum of positive squares in 2 ways, for example, as 55696 + 60025 = 236^2 + 245^2 .

It is a cyclic number.

It is not a de Polignac number, because 115721 - 2⁶ = 115657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 115721.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (115727) 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, 500 + ... + 693.

It is an arithmetic number, because the mean of its divisors is an integer number (29253).

2¹¹⁵⁷²¹ is an apocalyptic number.

It is an amenable number.

115721 is a deficient number, since it is larger than the sum of its proper divisors (1291).

115721 is an equidigital number, since it uses as much as digits as its factorization.

115721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290.

The product of its digits is 70, while the sum is 17.

The square root of 115721 is about 340.1778946375. The cubic root of 115721 is about 48.7308581434.

The spelling of 115721 in words is "one hundred fifteen thousand, seven hundred twenty-one".