81855419 has 2 divisors, whose sum is σ = 81855420. Its totient is φ = 81855418.

The previous prime is 81855377. The next prime is 81855457. The reversal of 81855419 is 91455818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81855419 - 2²⁴ = 65078203 is a prime.

It is a super-2 number, since 2×81855419² = 13400619239331122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81858419) 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, 40927709 + 40927710.

It is an arithmetic number, because the mean of its divisors is an integer number (40927710).

Almost surely, 2^81855419 is an apocalyptic number.

81855419 is a deficient number, since it is larger than the sum of its proper divisors (1).

81855419 is an equidigital number, since it uses as much as digits as its factorization.

81855419 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 57600, while the sum is 41.

The square root of 81855419 is about 9047.3984658575. The cubic root of 81855419 is about 434.1926611749.

The spelling of 81855419 in words is "eighty-one million, eight hundred fifty-five thousand, four hundred nineteen".