18139343221 has 2 divisors, whose sum is σ = 18139343222. Its totient is φ = 18139343220.

The previous prime is 18139343207. The next prime is 18139343267. The reversal of 18139343221 is 12234393181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11580772996 + 6558570225 = 107614^2 + 80985^2 .

It is an emirp because it is prime and its reverse (12234393181) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18139343221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18139343821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9069671610 + 9069671611.

It is an arithmetic number, because the mean of its divisors is an integer number (9069671611).

Almost surely, 2^18139343221 is an apocalyptic number.

It is an amenable number.

18139343221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18139343221 is an equidigital number, since it uses as much as digits as its factorization.

18139343221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 37.

The spelling of 18139343221 in words is "eighteen billion, one hundred thirty-nine million, three hundred forty-three thousand, two hundred twenty-one".