1813115561 has 8 divisors (see below), whose sum is σ = 1834253064. Its totient is φ = 1792028160.

The previous prime is 1813115543. The next prime is 1813115581. The reversal of 1813115561 is 1655113181.

It can be written as a sum of positive squares in 4 ways, for example, as 92525161 + 1720590400 = 9619^2 + 41480^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 1813115561 - 2⁶ = 1813115497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1813115581) 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, 62891 + ... + 87071.

It is an arithmetic number, because the mean of its divisors is an integer number (229281633).

Almost surely, 2^1813115561 is an apocalyptic number.

It is an amenable number.

1813115561 is a deficient number, since it is larger than the sum of its proper divisors (21137503).

1813115561 is an equidigital number, since it uses as much as digits as its factorization.

1813115561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25051.

The product of its digits is 3600, while the sum is 32.

The square root of 1813115561 is about 42580.6946984194. The cubic root of 1813115561 is about 1219.3877517886.

The spelling of 1813115561 in words is "one billion, eight hundred thirteen million, one hundred fifteen thousand, five hundred sixty-one".