18199421 has 2 divisors, whose sum is σ = 18199422. Its totient is φ = 18199420.

The previous prime is 18199381. The next prime is 18199429. The reversal of 18199421 is 12499181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17935225 + 264196 = 4235^2 + 514^2 .

It is an emirp because it is prime and its reverse (12499181) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18199421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18199429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9099710 + 9099711.

It is an arithmetic number, because the mean of its divisors is an integer number (9099711).

Almost surely, 2^18199421 is an apocalyptic number.

It is an amenable number.

18199421 is a deficient number, since it is larger than the sum of its proper divisors (1).

18199421 is an equidigital number, since it uses as much as digits as its factorization.

18199421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 35.

The square root of 18199421 is about 4266.0779411539. The cubic root of 18199421 is about 263.0384220059.

The spelling of 18199421 in words is "eighteen million, one hundred ninety-nine thousand, four hundred twenty-one".