18211219931 has 4 divisors (see below), whose sum is σ = 18212543712. Its totient is φ = 18209896152.

The previous prime is 18211219903. The next prime is 18211219967. The reversal of 18211219931 is 13991211281.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18211219931 - 2³⁰ = 17137478107 is a prime.

It is a super-2 number, since 2×18211219931² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18211219331) 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, 641036 + ... + 668841.

It is an arithmetic number, because the mean of its divisors is an integer number (4553135928).

Almost surely, 2^18211219931 is an apocalyptic number.

18211219931 is a deficient number, since it is larger than the sum of its proper divisors (1323781).

18211219931 is a wasteful number, since it uses less digits than its factorization.

18211219931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1323780.

The product of its digits is 7776, while the sum is 38.

The spelling of 18211219931 in words is "eighteen billion, two hundred eleven million, two hundred nineteen thousand, nine hundred thirty-one".