81371519 has 2 divisors, whose sum is σ = 81371520. Its totient is φ = 81371518.

The previous prime is 81371491. The next prime is 81371527. The reversal of 81371519 is 91517318.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81371519 is a prime.

It is a super-2 number, since 2×81371519² = 13242648208734722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81371599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40685759 + 40685760.

It is an arithmetic number, because the mean of its divisors is an integer number (40685760).

Almost surely, 2^81371519 is an apocalyptic number.

81371519 is a deficient number, since it is larger than the sum of its proper divisors (1).

81371519 is an equidigital number, since it uses as much as digits as its factorization.

81371519 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 35.

The square root of 81371519 is about 9020.6163314931. The cubic root of 81371519 is about 433.3353723112.

The spelling of 81371519 in words is "eighty-one million, three hundred seventy-one thousand, five hundred nineteen".