81998219 has 2 divisors, whose sum is σ = 81998220. Its totient is φ = 81998218.

The previous prime is 81998209. The next prime is 81998227. The reversal of 81998219 is 91289918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81998219 - 2⁸ = 81997963 is a prime.

It is a super-2 number, since 2×81998219² = 13447415838343922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81998209) 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, 40999109 + 40999110.

It is an arithmetic number, because the mean of its divisors is an integer number (40999110).

Almost surely, 2^81998219 is an apocalyptic number.

81998219 is a deficient number, since it is larger than the sum of its proper divisors (1).

81998219 is an equidigital number, since it uses as much as digits as its factorization.

81998219 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 93312, while the sum is 47.

The square root of 81998219 is about 9055.2867983295. The cubic root of 81998219 is about 434.4450032201.

The spelling of 81998219 in words is "eighty-one million, nine hundred ninety-eight thousand, two hundred nineteen".