81686741 has 2 divisors, whose sum is σ = 81686742. Its totient is φ = 81686740.

The previous prime is 81686729. The next prime is 81686743. The reversal of 81686741 is 14768618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 79584241 + 2102500 = 8921^2 + 1450^2 .

It is a cyclic number.

It is not a de Polignac number, because 81686741 - 2¹⁸ = 81424597 is a prime.

Together with 81686743, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81686743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40843370 + 40843371.

It is an arithmetic number, because the mean of its divisors is an integer number (40843371).

Almost surely, 2^81686741 is an apocalyptic number.

It is an amenable number.

81686741 is a deficient number, since it is larger than the sum of its proper divisors (1).

81686741 is an equidigital number, since it uses as much as digits as its factorization.

81686741 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 64512, while the sum is 41.

The square root of 81686741 is about 9038.0717523153. The cubic root of 81686741 is about 433.8942117237.

The spelling of 81686741 in words is "eighty-one million, six hundred eighty-six thousand, seven hundred forty-one".