18878673221 has 2 divisors, whose sum is σ = 18878673222. Its totient is φ = 18878673220.

The previous prime is 18878673197. The next prime is 18878673223. The reversal of 18878673221 is 12237687881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18848544100 + 30129121 = 137290^2 + 5489^2 .

It is a cyclic number.

It is not a de Polignac number, because 18878673221 - 2⁶ = 18878673157 is a prime.

Together with 18878673223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18878673223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9439336610 + 9439336611.

It is an arithmetic number, because the mean of its divisors is an integer number (9439336611).

Almost surely, 2^18878673221 is an apocalyptic number.

It is an amenable number.

18878673221 is a deficient number, since it is larger than the sum of its proper divisors (1).

18878673221 is an equidigital number, since it uses as much as digits as its factorization.

18878673221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1806336, while the sum is 53.

The spelling of 18878673221 in words is "eighteen billion, eight hundred seventy-eight million, six hundred seventy-three thousand, two hundred twenty-one".