81145717 has 2 divisors, whose sum is σ = 81145718. Its totient is φ = 81145716.

The previous prime is 81145651. The next prime is 81145721. The reversal of 81145717 is 71754118.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74545956 + 6599761 = 8634^2 + 2569^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81145717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81145787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40572858 + 40572859.

It is an arithmetic number, because the mean of its divisors is an integer number (40572859).

Almost surely, 2^81145717 is an apocalyptic number.

It is an amenable number.

81145717 is a deficient number, since it is larger than the sum of its proper divisors (1).

81145717 is an equidigital number, since it uses as much as digits as its factorization.

81145717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7840, while the sum is 34.

The square root of 81145717 is about 9008.0917513089. The cubic root of 81145717 is about 432.9341727985.

It can be divided in two parts, 8114 and 5717, that added together give a palindrome (13831).

The spelling of 81145717 in words is "eighty-one million, one hundred forty-five thousand, seven hundred seventeen".