18219919 has 2 divisors, whose sum is σ = 18219920. Its totient is φ = 18219918.

The previous prime is 18219899. The next prime is 18219923. The reversal of 18219919 is 91991281.

It is a strong prime.

It is an emirp because it is prime and its reverse (91991281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18219919 - 2⁷ = 18219791 is a prime.

It is a super-2 number, since 2×18219919² = 663930896733122, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18219959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9109959 + 9109960.

It is an arithmetic number, because the mean of its divisors is an integer number (9109960).

Almost surely, 2^18219919 is an apocalyptic number.

18219919 is a deficient number, since it is larger than the sum of its proper divisors (1).

18219919 is an equidigital number, since it uses as much as digits as its factorization.

18219919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 40.

The square root of 18219919 is about 4268.4797059375. The cubic root of 18219919 is about 263.1371383075.

The spelling of 18219919 in words is "eighteen million, two hundred nineteen thousand, nine hundred nineteen".