199518382421 has 2 divisors, whose sum is σ = 199518382422. Its totient is φ = 199518382420.

The previous prime is 199518382391. The next prime is 199518382423. The reversal of 199518382421 is 124283815991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 113074150225 + 86444232196 = 336265^2 + 294014^2 .

It is an emirp because it is prime and its reverse (124283815991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199518382421 - 2¹⁰ = 199518381397 is a prime.

Together with 199518382423, 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 (199518382423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99759191210 + 99759191211.

It is an arithmetic number, because the mean of its divisors is an integer number (99759191211).

Almost surely, 2^199518382421 is an apocalyptic number.

It is an amenable number.

199518382421 is a deficient number, since it is larger than the sum of its proper divisors (1).

199518382421 is an equidigital number, since it uses as much as digits as its factorization.

199518382421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 53.

The spelling of 199518382421 in words is "one hundred ninety-nine billion, five hundred eighteen million, three hundred eighty-two thousand, four hundred twenty-one".