81340657 has 2 divisors, whose sum is σ = 81340658. Its totient is φ = 81340656.

The previous prime is 81340619. The next prime is 81340661. The reversal of 81340657 is 75604318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 68409441 + 12931216 = 8271^2 + 3596^2 .

It is a cyclic number.

It is not a de Polignac number, because 81340657 - 2¹⁹ = 80816369 is a prime.

It is not a weakly prime, because it can be changed into another prime (81340607) 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, 40670328 + 40670329.

It is an arithmetic number, because the mean of its divisors is an integer number (40670329).

Almost surely, 2^81340657 is an apocalyptic number.

It is an amenable number.

81340657 is a deficient number, since it is larger than the sum of its proper divisors (1).

81340657 is an equidigital number, since it uses as much as digits as its factorization.

81340657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 81340657 is about 9018.9055322694. The cubic root of 81340657 is about 433.2805812839.

The spelling of 81340657 in words is "eighty-one million, three hundred forty thousand, six hundred fifty-seven".