81859291 has 2 divisors, whose sum is σ = 81859292. Its totient is φ = 81859290.

The previous prime is 81859181. The next prime is 81859303. The reversal of 81859291 is 19295818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81859291 - 2¹⁵ = 81826523 is a prime.

It is not a weakly prime, because it can be changed into another prime (81859091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40929645 + 40929646.

It is an arithmetic number, because the mean of its divisors is an integer number (40929646).

Almost surely, 2^81859291 is an apocalyptic number.

81859291 is a deficient number, since it is larger than the sum of its proper divisors (1).

81859291 is an equidigital number, since it uses as much as digits as its factorization.

81859291 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 43.

The square root of 81859291 is about 9047.6124474913. The cubic root of 81859291 is about 434.1995072599.

The spelling of 81859291 in words is "eighty-one million, eight hundred fifty-nine thousand, two hundred ninety-one".