81361597 has 2 divisors, whose sum is σ = 81361598. Its totient is φ = 81361596.

The previous prime is 81361561. The next prime is 81361619. The reversal of 81361597 is 79516318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77898276 + 3463321 = 8826^2 + 1861^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81361597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81361297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40680798 + 40680799.

It is an arithmetic number, because the mean of its divisors is an integer number (40680799).

Almost surely, 2^81361597 is an apocalyptic number.

It is an amenable number.

81361597 is a deficient number, since it is larger than the sum of its proper divisors (1).

81361597 is an equidigital number, since it uses as much as digits as its factorization.

81361597 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 40.

The square root of 81361597 is about 9020.0663523058. The cubic root of 81361597 is about 433.3177587433.

The spelling of 81361597 in words is "eighty-one million, three hundred sixty-one thousand, five hundred ninety-seven".