18381221243 has 16 divisors (see below), whose sum is σ = 24122999040. Its totient is φ = 13569184800.

The previous prime is 18381221237. The next prime is 18381221263. The reversal of 18381221243 is 34212218381.

It is a cyclic number.

It is not a de Polignac number, because 18381221243 - 2⁶ = 18381221179 is a prime.

It is a super-2 number, since 2×18381221243² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18381221263) 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, 6280568 + ... + 6283493.

It is an arithmetic number, because the mean of its divisors is an integer number (1507687440).

Almost surely, 2^18381221243 is an apocalyptic number.

18381221243 is a deficient number, since it is larger than the sum of its proper divisors (5741777797).

18381221243 is a wasteful number, since it uses less digits than its factorization.

18381221243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12564098.

The product of its digits is 18432, while the sum is 35.

The spelling of 18381221243 in words is "eighteen billion, three hundred eighty-one million, two hundred twenty-one thousand, two hundred forty-three".