81307313 has 2 divisors, whose sum is σ = 81307314. Its totient is φ = 81307312.

The previous prime is 81307307. The next prime is 81307319. The reversal of 81307313 is 31370318.

It is a balanced prime because it is at equal distance from previous prime (81307307) and next prime (81307319).

It can be written as a sum of positive squares in only one way, i.e., 81306289 + 1024 = 9017^2 + 32^2 .

It is a cyclic number.

It is not a de Polignac number, because 81307313 - 2⁴ = 81307297 is a prime.

It is a super-2 number, since 2×81307313² = 13221758294559938, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81307319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40653656 + 40653657.

It is an arithmetic number, because the mean of its divisors is an integer number (40653657).

Almost surely, 2^81307313 is an apocalyptic number.

It is an amenable number.

81307313 is a deficient number, since it is larger than the sum of its proper divisors (1).

81307313 is an equidigital number, since it uses as much as digits as its factorization.

81307313 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 81307313 is about 9017.0567814559. The cubic root of 81307313 is about 433.2213682458.

The spelling of 81307313 in words is "eighty-one million, three hundred seven thousand, three hundred thirteen".