81371705 has 4 divisors (see below), whose sum is σ = 97646052. Its totient is φ = 65097360.

The previous prime is 81371671. The next prime is 81371747. The reversal of 81371705 is 50717318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50717318 = 2 ⋅25358659.

It can be written as a sum of positive squares in 2 ways, for example, as 17707264 + 63664441 = 4208^2 + 7979^2 .

It is not a de Polignac number, because 81371705 - 2²⁰ = 80323129 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 8137166 + ... + 8137175.

It is an arithmetic number, because the mean of its divisors is an integer number (24411513).

Almost surely, 2^81371705 is an apocalyptic number.

It is an amenable number.

81371705 is a deficient number, since it is larger than the sum of its proper divisors (16274347).

81371705 is a wasteful number, since it uses less digits than its factorization.

81371705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16274346.

The product of its (nonzero) digits is 5880, while the sum is 32.

The square root of 81371705 is about 9020.6266412040. The cubic root of 81371705 is about 433.3357024854.

The spelling of 81371705 in words is "eighty-one million, three hundred seventy-one thousand, seven hundred five".