115156721 has 4 divisors (see below), whose sum is σ = 117606912. Its totient is φ = 112706532.

The previous prime is 115156673. The next prime is 115156733. The reversal of 115156721 is 127651511.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 127651511 = 13 ⋅9819347.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-115156721 is a prime.

It is a super-2 number, since 2×115156721² = 26522140782943682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (115156421) 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, 1225025 + ... + 1225118.

It is an arithmetic number, because the mean of its divisors is an integer number (29401728).

Almost surely, 2^115156721 is an apocalyptic number.

It is an amenable number.

115156721 is a deficient number, since it is larger than the sum of its proper divisors (2450191).

115156721 is an equidigital number, since it uses as much as digits as its factorization.

115156721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2450190.

The product of its digits is 2100, while the sum is 29.

The square root of 115156721 is about 10731.1099612295. The cubic root of 115156721 is about 486.5152187683.

The spelling of 115156721 in words is "one hundred fifteen million, one hundred fifty-six thousand, seven hundred twenty-one".