81684818 has 8 divisors (see below), whose sum is σ = 123651660. Its totient is φ = 40467600.

The previous prime is 81684817. The next prime is 81684839. The reversal of 81684818 is 81848618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 68674369 + 13010449 = 8287^2 + 3607^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81684817) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 187133 + ... + 187568.

Almost surely, 2^81684818 is an apocalyptic number.

81684818 is a deficient number, since it is larger than the sum of its proper divisors (41966842).

81684818 is a wasteful number, since it uses less digits than its factorization.

81684818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 374812.

The product of its digits is 98304, while the sum is 44.

The square root of 81684818 is about 9037.9653683780. The cubic root of 81684818 is about 433.8908069071.

The spelling of 81684818 in words is "eighty-one million, six hundred eighty-four thousand, eight hundred eighteen".