81318019 has 2 divisors, whose sum is σ = 81318020. Its totient is φ = 81318018.

The previous prime is 81318011. The next prime is 81318023. The reversal of 81318019 is 91081318.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81318019 - 2³ = 81318011 is a prime.

It is a super-2 number, since 2×81318019² = 13225240428168722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81318011) 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, 40659009 + 40659010.

It is an arithmetic number, because the mean of its divisors is an integer number (40659010).

Almost surely, 2^81318019 is an apocalyptic number.

81318019 is a deficient number, since it is larger than the sum of its proper divisors (1).

81318019 is an equidigital number, since it uses as much as digits as its factorization.

81318019 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 31.

The square root of 81318019 is about 9017.6504146036. The cubic root of 81318019 is about 433.2403819697.

The spelling of 81318019 in words is "eighty-one million, three hundred eighteen thousand, nineteen".