81666333 has 16 divisors (see below), whose sum is σ = 138271360. Its totient is φ = 46666368.

The previous prime is 81666323. The next prime is 81666379. The reversal of 81666333 is 33366618.

It is not a de Polignac number, because 81666333 - 2¹³ = 81658141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81666323) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 215860 + ... + 216237.

It is an arithmetic number, because the mean of its divisors is an integer number (8641960).

Almost surely, 2^81666333 is an apocalyptic number.

It is an amenable number.

81666333 is a deficient number, since it is larger than the sum of its proper divisors (56605027).

81666333 is a wasteful number, since it uses less digits than its factorization.

81666333 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 432113 (or 432107 counting only the distinct ones).

The product of its digits is 46656, while the sum is 36.

The square root of 81666333 is about 9036.9426799112. The cubic root of 81666333 is about 433.8580750938.

The spelling of 81666333 in words is "eighty-one million, six hundred sixty-six thousand, three hundred thirty-three".