81244836 has 144 divisors (see below), whose sum is σ = 237249600. Its totient is φ = 23970816.

The previous prime is 81244781. The next prime is 81244861. The reversal of 81244836 is 63844218.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81244836.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 592960 + ... + 593096.

Almost surely, 2^81244836 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 81244836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118624800).

81244836 is an abundant number, since it is smaller than the sum of its proper divisors (156004764).

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

81244836 is a wasteful number, since it uses less digits than its factorization.

81244836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203 (or 178 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 81244836 is about 9013.5917369271. The cubic root of 81244836 is about 433.1103765607.

The spelling of 81244836 in words is "eighty-one million, two hundred forty-four thousand, eight hundred thirty-six".