81740861 has 2 divisors, whose sum is σ = 81740862. Its totient is φ = 81740860.

The previous prime is 81740851. The next prime is 81740891. The reversal of 81740861 is 16804718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50324836 + 31416025 = 7094^2 + 5605^2 .

It is a cyclic number.

It is not a de Polignac number, because 81740861 - 2¹⁰ = 81739837 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81740851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40870430 + 40870431.

It is an arithmetic number, because the mean of its divisors is an integer number (40870431).

Almost surely, 2^81740861 is an apocalyptic number.

It is an amenable number.

81740861 is a deficient number, since it is larger than the sum of its proper divisors (1).

81740861 is an equidigital number, since it uses as much as digits as its factorization.

81740861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 35.

The square root of 81740861 is about 9041.0652580324. The cubic root of 81740861 is about 433.9900133615.

The spelling of 81740861 in words is "eighty-one million, seven hundred forty thousand, eight hundred sixty-one".