18555880981 has 4 divisors (see below), whose sum is σ = 20242779264. Its totient is φ = 16868982700.

The previous prime is 18555880969. The next prime is 18555880991. The reversal of 18555880981 is 18908855581.

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.

It is a cyclic number.

It is not a de Polignac number, because 18555880981 - 2¹³ = 18555872789 is a prime.

It is a super-2 number, since 2×18555880981² (a number of 21 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (58) 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18555880961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 843449125 + ... + 843449146.

It is an arithmetic number, because the mean of its divisors is an integer number (5060694816).

Almost surely, 2^18555880981 is an apocalyptic number.

18555880981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18555880981 is a deficient number, since it is larger than the sum of its proper divisors (1686898283).

18555880981 is a wasteful number, since it uses less digits than its factorization.

18555880981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1686898282.

The product of its (nonzero) digits is 4608000, while the sum is 58.

The spelling of 18555880981 in words is "eighteen billion, five hundred fifty-five million, eight hundred eighty thousand, nine hundred eighty-one".