81918333 has 48 divisors (see below), whose sum is σ = 140564736. Its totient is φ = 44997120.

The previous prime is 81918323. The next prime is 81918349. The reversal of 81918333 is 33381918.

It is not a de Polignac number, because 81918333 - 2¹⁰ = 81917309 is a prime.

It is a super-2 number, since 2×81918333² = 13421226562997778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81918323) 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 in 47 ways as a sum of consecutive naturals, for example, 263248 + ... + 263558.

It is an arithmetic number, because the mean of its divisors is an integer number (2928432).

Almost surely, 2^81918333 is an apocalyptic number.

It is an amenable number.

81918333 is a deficient number, since it is larger than the sum of its proper divisors (58646403).

81918333 is a wasteful number, since it uses less digits than its factorization.

81918333 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474 (or 471 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 81918333 is about 9050.8747091096. The cubic root of 81918333 is about 434.3038727145.

The spelling of 81918333 in words is "eighty-one million, nine hundred eighteen thousand, three hundred thirty-three".