81368593 has 2 divisors, whose sum is σ = 81368594. Its totient is φ = 81368592.

The previous prime is 81368591. The next prime is 81368653. The reversal of 81368593 is 39586318.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75742209 + 5626384 = 8703^2 + 2372^2 .

It is a cyclic number.

It is not a de Polignac number, because 81368593 - 2¹ = 81368591 is a prime.

Together with 81368591, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81368591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40684296 + 40684297.

It is an arithmetic number, because the mean of its divisors is an integer number (40684297).

Almost surely, 2^81368593 is an apocalyptic number.

It is an amenable number.

81368593 is a deficient number, since it is larger than the sum of its proper divisors (1).

81368593 is an equidigital number, since it uses as much as digits as its factorization.

81368593 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 43.

The square root of 81368593 is about 9020.4541459951. The cubic root of 81368593 is about 433.3301782150.

The spelling of 81368593 in words is "eighty-one million, three hundred sixty-eight thousand, five hundred ninety-three".