81085432291 has 2 divisors, whose sum is σ = 81085432292. Its totient is φ = 81085432290.

The previous prime is 81085432279. The next prime is 81085432357. The reversal of 81085432291 is 19223458018.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81085432291 - 2⁷ = 81085432163 is a prime.

It is not a weakly prime, because it can be changed into another prime (81085432201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40542716145 + 40542716146.

It is an arithmetic number, because the mean of its divisors is an integer number (40542716146).

Almost surely, 2^81085432291 is an apocalyptic number.

81085432291 is a deficient number, since it is larger than the sum of its proper divisors (1).

81085432291 is an equidigital number, since it uses as much as digits as its factorization.

81085432291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 138240, while the sum is 43.

The spelling of 81085432291 in words is "eighty-one billion, eighty-five million, four hundred thirty-two thousand, two hundred ninety-one".