115651561 has 4 divisors (see below), whose sum is σ = 122454612. Its totient is φ = 108848512.

The previous prime is 115651541. The next prime is 115651589. The reversal of 115651561 is 165156511.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165156511 = 13 ⋅12704347.

It can be written as a sum of positive squares in 2 ways, for example, as 108056025 + 7595536 = 10395^2 + 2756^2 .

It is a cyclic number.

It is not a de Polignac number, because 115651561 - 2⁷ = 115651433 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (115651511) 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, 3401500 + ... + 3401533.

It is an arithmetic number, because the mean of its divisors is an integer number (30613653).

Almost surely, 2^115651561 is an apocalyptic number.

It is an amenable number.

115651561 is a deficient number, since it is larger than the sum of its proper divisors (6803051).

115651561 is an equidigital number, since it uses as much as digits as its factorization.

115651561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6803050.

The product of its digits is 4500, while the sum is 31.

The square root of 115651561 is about 10754.1415742959. The cubic root of 115651561 is about 487.2110912319.

The spelling of 115651561 in words is "one hundred fifteen million, six hundred fifty-one thousand, five hundred sixty-one".