18987881121 has 12 divisors (see below), whose sum is σ = 29920297680. Its totient is φ = 11507806680.

The previous prime is 18987881119. The next prime is 18987881161. The reversal of 18987881121 is 12118878981.

It is not a de Polignac number, because 18987881121 - 2¹ = 18987881119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18987881161) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 95898291 + ... + 95898488.

It is an arithmetic number, because the mean of its divisors is an integer number (2493358140).

Almost surely, 2^18987881121 is an apocalyptic number.

18987881121 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18987881121 is a deficient number, since it is larger than the sum of its proper divisors (10932416559).

18987881121 is a wasteful number, since it uses less digits than its factorization.

18987881121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191796796 (or 191796793 counting only the distinct ones).

The product of its digits is 516096, while the sum is 54.

The spelling of 18987881121 in words is "eighteen billion, nine hundred eighty-seven million, eight hundred eighty-one thousand, one hundred twenty-one".