81730944 has 80 divisors (see below), whose sum is σ = 243260820. Its totient is φ = 27240192.

The previous prime is 81730931. The next prime is 81730963. The reversal of 81730944 is 44903718.

It is a happy number.

It is a super-2 number, since 2×81730944² = 13359894414262272, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 81730899 and 81730908.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 6427 + ... + 14309.

Almost surely, 2^81730944 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 81730944, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121630410).

81730944 is an abundant number, since it is smaller than the sum of its proper divisors (161529876).

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

81730944 is an equidigital number, since it uses as much as digits as its factorization.

81730944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7909 (or 7888 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 81730944 is about 9040.5167993871. The cubic root of 81730944 is about 433.9724617438.

It can be divided in two parts, 81 and 730944, that added together give a square (731025 = 855²).

The spelling of 81730944 in words is "eighty-one million, seven hundred thirty thousand, nine hundred forty-four".