81396613 has 2 divisors, whose sum is σ = 81396614. Its totient is φ = 81396612.

The previous prime is 81396599. The next prime is 81396619. The reversal of 81396613 is 31669318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70526404 + 10870209 = 8398^2 + 3297^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81396613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81396619) 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, 40698306 + 40698307.

It is an arithmetic number, because the mean of its divisors is an integer number (40698307).

Almost surely, 2^81396613 is an apocalyptic number.

It is an amenable number.

81396613 is a deficient number, since it is larger than the sum of its proper divisors (1).

81396613 is an equidigital number, since it uses as much as digits as its factorization.

81396613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 37.

The square root of 81396613 is about 9022.0071491880. The cubic root of 81396613 is about 433.3799128759.

The spelling of 81396613 in words is "eighty-one million, three hundred ninety-six thousand, six hundred thirteen".