18821399 has 2 divisors, whose sum is σ = 18821400. Its totient is φ = 18821398.

The previous prime is 18821389. The next prime is 18821417. The reversal of 18821399 is 99312881.

It is a weak prime.

It is an emirp because it is prime and its reverse (99312881) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18821399 - 2²⁰ = 17772823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18821389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9410699 + 9410700.

It is an arithmetic number, because the mean of its divisors is an integer number (9410700).

Almost surely, 2^18821399 is an apocalyptic number.

18821399 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821399 is an equidigital number, since it uses as much as digits as its factorization.

18821399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 41.

The square root of 18821399 is about 4338.3636316012. The cubic root of 18821399 is about 266.0014274331.

The spelling of 18821399 in words is "eighteen million, eight hundred twenty-one thousand, three hundred ninety-nine".