81817424 has 60 divisors (see below), whose sum is σ = 175194516. Its totient is φ = 36793344.

The previous prime is 81817399. The next prime is 81817453. The reversal of 81817424 is 42471818.

It can be written as a sum of positive squares in 2 ways, for example, as 5569600 + 76247824 = 2360^2 + 8732^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 723992 + ... + 724104.

Almost surely, 2^81817424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81817424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (87597258).

81817424 is an abundant number, since it is smaller than the sum of its proper divisors (93377092).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81817424 is a wasteful number, since it uses less digits than its factorization.

81817424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 187 counting only the distinct ones).

The product of its digits is 14336, while the sum is 35.

The square root of 81817424 is about 9045.2984472598. The cubic root of 81817424 is about 434.1254707411.

The spelling of 81817424 in words is "eighty-one million, eight hundred seventeen thousand, four hundred twenty-four".