81716749 has 2 divisors, whose sum is σ = 81716750. Its totient is φ = 81716748.

The previous prime is 81716699. The next prime is 81716827. The reversal of 81716749 is 94761718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75811849 + 5904900 = 8707^2 + 2430^2 .

It is a cyclic number.

It is not a de Polignac number, because 81716749 - 2⁹ = 81716237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81716449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40858374 + 40858375.

It is an arithmetic number, because the mean of its divisors is an integer number (40858375).

Almost surely, 2^81716749 is an apocalyptic number.

It is an amenable number.

81716749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81716749 is an equidigital number, since it uses as much as digits as its factorization.

81716749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84672, while the sum is 43.

The square root of 81716749 is about 9039.7316884961. The cubic root of 81716749 is about 433.9473362305.

It can be divided in two parts, 817167 and 49, that added together give a square (817216 = 904²).

The spelling of 81716749 in words is "eighty-one million, seven hundred sixteen thousand, seven hundred forty-nine".