81866827 has 4 divisors (see below), whose sum is σ = 93562096. Its totient is φ = 70171560.

The previous prime is 81866789. The next prime is 81866857. The reversal of 81866827 is 72866818.

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

It is a cyclic number.

It is not a de Polignac number, because 81866827 - 2¹¹ = 81864779 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81866857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5847624 + ... + 5847637.

It is an arithmetic number, because the mean of its divisors is an integer number (23390524).

Almost surely, 2^81866827 is an apocalyptic number.

81866827 is a deficient number, since it is larger than the sum of its proper divisors (11695269).

81866827 is a wasteful number, since it uses less digits than its factorization.

81866827 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11695268.

The product of its digits is 258048, while the sum is 46.

The square root of 81866827 is about 9048.0289013685. The cubic root of 81866827 is about 434.2128310462.

Subtracting from 81866827 its reverse (72866818), we obtain a palindrome (9000009).

The spelling of 81866827 in words is "eighty-one million, eight hundred sixty-six thousand, eight hundred twenty-seven".