81705229 has 2 divisors, whose sum is σ = 81705230. Its totient is φ = 81705228.

The previous prime is 81705191. The next prime is 81705259. The reversal of 81705229 is 92250718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54686025 + 27019204 = 7395^2 + 5198^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81705229 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81705194 and 81705203.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81705259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40852614 + 40852615.

It is an arithmetic number, because the mean of its divisors is an integer number (40852615).

Almost surely, 2^81705229 is an apocalyptic number.

It is an amenable number.

81705229 is a deficient number, since it is larger than the sum of its proper divisors (1).

81705229 is an equidigital number, since it uses as much as digits as its factorization.

81705229 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 81705229 is about 9039.0944789841. The cubic root of 81705229 is about 433.9269433967.

The spelling of 81705229 in words is "eighty-one million, seven hundred five thousand, two hundred twenty-nine".