81308593 has 2 divisors, whose sum is σ = 81308594. Its totient is φ = 81308592.

The previous prime is 81308537. The next prime is 81308599. The reversal of 81308593 is 39580318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81306289 + 2304 = 9017^2 + 48^2 .

It is a cyclic number.

It is not a de Polignac number, because 81308593 - 2⁹ = 81308081 is a prime.

It is a super-2 number, since 2×81308593² = 13222174591279298, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81308599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40654296 + 40654297.

It is an arithmetic number, because the mean of its divisors is an integer number (40654297).

Almost surely, 2^81308593 is an apocalyptic number.

It is an amenable number.

81308593 is a deficient number, since it is larger than the sum of its proper divisors (1).

81308593 is an equidigital number, since it uses as much as digits as its factorization.

81308593 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 81308593 is about 9017.1277577730. The cubic root of 81308593 is about 433.2236415978.

The spelling of 81308593 in words is "eighty-one million, three hundred eight thousand, five hundred ninety-three".