81327805 has 16 divisors (see below), whose sum is σ = 107667504. Its totient is φ = 58590720.

The previous prime is 81327791. The next prime is 81327821. The reversal of 81327805 is 50872318.

It can be written as a sum of positive squares in 8 ways, for example, as 51538041 + 29789764 = 7179^2 + 5458^2 .

It is not a de Polignac number, because 81327805 - 2⁹ = 81327293 is a prime.

It is a super-2 number, since 2×81327805² = 13228423732236050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 12594 + ... + 17923.

It is an arithmetic number, because the mean of its divisors is an integer number (6729219).

Almost surely, 2^81327805 is an apocalyptic number.

It is an amenable number.

81327805 is a deficient number, since it is larger than the sum of its proper divisors (26339699).

81327805 is a wasteful number, since it uses less digits than its factorization.

81327805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30576.

The product of its (nonzero) digits is 13440, while the sum is 34.

The square root of 81327805 is about 9018.1930008178. The cubic root of 81327805 is about 433.2577603252.

The spelling of 81327805 in words is "eighty-one million, three hundred twenty-seven thousand, eight hundred five".