18713121138209 has 2 divisors, whose sum is σ = 18713121138210. Its totient is φ = 18713121138208.

The previous prime is 18713121138181. The next prime is 18713121138223. The reversal of 18713121138209 is 90283112131781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14399960593984 + 4313160544225 = 3794728^2 + 2076815^2 .

It is a cyclic number.

It is not a de Polignac number, because 18713121138209 - 2⁴⁰ = 17613609510433 is a prime.

It is not a weakly prime, because it can be changed into another prime (18713121138109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9356560569104 + 9356560569105.

It is an arithmetic number, because the mean of its divisors is an integer number (9356560569105).

Almost surely, 2^{18713121138209} is an apocalyptic number.

It is an amenable number.

18713121138209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18713121138209 is an equidigital number, since it uses as much as digits as its factorization.

18713121138209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 47.

The spelling of 18713121138209 in words is "eighteen trillion, seven hundred thirteen billion, one hundred twenty-one million, one hundred thirty-eight thousand, two hundred nine".