81271786 has 4 divisors (see below), whose sum is σ = 121907682. Its totient is φ = 40635892.

The previous prime is 81271777. The next prime is 81271787. The reversal of 81271786 is 68717218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 55577025 + 25694761 = 7455^2 + 5069^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81271787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20317945 + ... + 20317948.

Almost surely, 2^81271786 is an apocalyptic number.

81271786 is a deficient number, since it is larger than the sum of its proper divisors (40635896).

81271786 is a wasteful number, since it uses less digits than its factorization.

81271786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40635895.

The product of its digits is 37632, while the sum is 40.

The square root of 81271786 is about 9015.0865775099. The cubic root of 81271786 is about 433.1582607703.

The spelling of 81271786 in words is "eighty-one million, two hundred seventy-one thousand, seven hundred eighty-six".