5518391881 has 4 divisors (see below), whose sum is σ = 5520622212. Its totient is φ = 5516161552.

The previous prime is 5518391873. The next prime is 5518391917. The reversal of 5518391881 is 1881938155.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1881938155 = 5 ⋅376387631.

It can be written as a sum of positive squares in 2 ways, for example, as 1841182281 + 3677209600 = 42909^2 + 60640^2 .

It is a cyclic number.

It is not a de Polignac number, because 5518391881 - 2³ = 5518391873 is a prime.

It is a super-2 number, since 2×5518391881² = 60905297904573436322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) 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 (5518391821) 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, 1111450 + ... + 1116403.

It is an arithmetic number, because the mean of its divisors is an integer number (1380155553).

Almost surely, 2^5518391881 is an apocalyptic number.

It is an amenable number.

5518391881 is a deficient number, since it is larger than the sum of its proper divisors (2230331).

5518391881 is a wasteful number, since it uses less digits than its factorization.

5518391881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2230330.

The product of its digits is 345600, while the sum is 49.

The square root of 5518391881 is about 74285.8794186351. The cubic root of 5518391881 is about 1767.1395466349.

The spelling of 5518391881 in words is "five billion, five hundred eighteen million, three hundred ninety-one thousand, eight hundred eighty-one".