81818624 has 22 divisors (see below), whose sum is σ = 163559394. Its totient is φ = 40908800.

The previous prime is 81818623. The next prime is 81818687. The reversal of 81818624 is 42681818.

It can be written as a sum of positive squares in only one way, i.e., 64513024 + 17305600 = 8032^2 + 4160^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81818621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38927 + ... + 40974.

Almost surely, 2^81818624 is an apocalyptic number.

It is an amenable number.

81818624 is a deficient number, since it is larger than the sum of its proper divisors (81740770).

81818624 is an equidigital number, since it uses as much as digits as its factorization.

81818624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79921 (or 79903 counting only the distinct ones).

The product of its digits is 24576, while the sum is 38.

The square root of 81818624 is about 9045.3647798196. The cubic root of 81818624 is about 434.1275931416.

The spelling of 81818624 in words is "eighty-one million, eight hundred eighteen thousand, six hundred twenty-four".