81924218 has 8 divisors (see below), whose sum is σ = 122933460. Its totient is φ = 40946400.

The previous prime is 81924211. The next prime is 81924221. The reversal of 81924218 is 81242918.

It can be written as a sum of positive squares in 2 ways, for example, as 65334889 + 16589329 = 8083^2 + 4073^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81924211) 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, 398 + ... + 12806.

Almost surely, 2^81924218 is an apocalyptic number.

81924218 is a deficient number, since it is larger than the sum of its proper divisors (41009242).

81924218 is a wasteful number, since it uses less digits than its factorization.

81924218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15712.

The product of its digits is 9216, while the sum is 35.

The square root of 81924218 is about 9051.1998099699. The cubic root of 81924218 is about 434.3142725725.

The spelling of 81924218 in words is "eighty-one million, nine hundred twenty-four thousand, two hundred eighteen".