81591417 has 12 divisors (see below), whose sum is σ = 118260324. Its totient is φ = 54206880.

The previous prime is 81591383. The next prime is 81591431. The reversal of 81591417 is 71419518.

It can be written as a sum of positive squares in 2 ways, for example, as 53934336 + 27657081 = 7344^2 + 5259^2 .

It is not a de Polignac number, because 81591417 - 2¹² = 81587321 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81591457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12834 + ... + 18107.

It is an arithmetic number, because the mean of its divisors is an integer number (9855027).

Almost surely, 2^81591417 is an apocalyptic number.

It is an amenable number.

81591417 is a deficient number, since it is larger than the sum of its proper divisors (36668907).

81591417 is a wasteful number, since it uses less digits than its factorization.

81591417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31240 (or 31237 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 81591417 is about 9032.7967429805. The cubic root of 81591417 is about 433.7253690194.

The spelling of 81591417 in words is "eighty-one million, five hundred ninety-one thousand, four hundred seventeen".