18321920091 has 16 divisors (see below), whose sum is σ = 27341719200. Its totient is φ = 12125453184.

The previous prime is 18321920041. The next prime is 18321920093. The reversal of 18321920091 is 19002912381.

It is not a de Polignac number, because 18321920091 - 2⁶ = 18321920027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18321920093) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2472906 + ... + 2480303.

It is an arithmetic number, because the mean of its divisors is an integer number (1708857450).

Almost surely, 2^18321920091 is an apocalyptic number.

18321920091 is a deficient number, since it is larger than the sum of its proper divisors (9019799109).

18321920091 is a wasteful number, since it uses less digits than its factorization.

18321920091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4953355 (or 4953349 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The spelling of 18321920091 in words is "eighteen billion, three hundred twenty-one million, nine hundred twenty thousand, ninety-one".