81182666 has 4 divisors (see below), whose sum is σ = 121774002. Its totient is φ = 40591332.

The previous prime is 81182623. The next prime is 81182669. The reversal of 81182666 is 66628118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 66628118 = 2 ⋅33314059.

It can be written as a sum of positive squares in only one way, i.e., 76650025 + 4532641 = 8755^2 + 2129^2 .

It is not an unprimeable number, because it can be changed into a prime (81182669) by changing a digit.

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 as a sum of consecutive naturals, namely, 20295665 + ... + 20295668.

Almost surely, 2^81182666 is an apocalyptic number.

81182666 is a deficient number, since it is larger than the sum of its proper divisors (40591336).

81182666 is a wasteful number, since it uses less digits than its factorization.

81182666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40591335.

The product of its digits is 27648, while the sum is 38.

The square root of 81182666 is about 9010.1423962111. The cubic root of 81182666 is about 432.9998737703. Note that the first 3 decimals are identical.

The spelling of 81182666 in words is "eighty-one million, one hundred eighty-two thousand, six hundred sixty-six".