81344817 has 20 divisors (see below), whose sum is σ = 121815540. Its totient is φ = 54095904.

The previous prime is 81344807. The next prime is 81344831. The reversal of 81344817 is 71844318.

It can be written as a sum of positive squares in 2 ways, for example, as 42107121 + 39237696 = 6489^2 + 6264^2 .

It is not a de Polignac number, because 81344817 - 2⁴ = 81344801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81344807) 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 in 19 ways as a sum of consecutive naturals, for example, 40243 + ... + 42215.

It is an arithmetic number, because the mean of its divisors is an integer number (6090777).

Almost surely, 2^81344817 is an apocalyptic number.

It is an amenable number.

81344817 is a deficient number, since it is larger than the sum of its proper divisors (40470723).

81344817 is a wasteful number, since it uses less digits than its factorization.

81344817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2494 (or 2485 counting only the distinct ones).

The product of its digits is 21504, while the sum is 36.

The square root of 81344817 is about 9019.1361559741. The cubic root of 81344817 is about 433.2879675717.

The spelling of 81344817 in words is "eighty-one million, three hundred forty-four thousand, eight hundred seventeen".