81716647 has 2 divisors, whose sum is σ = 81716648. Its totient is φ = 81716646.

The previous prime is 81716633. The next prime is 81716681. The reversal of 81716647 is 74661718.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81716647 is a prime.

It is a super-2 number, since 2×81716647² = 13355220793845218, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81716147) 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, 40858323 + 40858324.

It is an arithmetic number, because the mean of its divisors is an integer number (40858324).

Almost surely, 2^81716647 is an apocalyptic number.

81716647 is a deficient number, since it is larger than the sum of its proper divisors (1).

81716647 is an equidigital number, since it uses as much as digits as its factorization.

81716647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 56448, while the sum is 40.

The square root of 81716647 is about 9039.7260467339. The cubic root of 81716647 is about 433.9471556773.

The spelling of 81716647 in words is "eighty-one million, seven hundred sixteen thousand, six hundred forty-seven".