81730770 has 64 divisors (see below), whose sum is σ = 218070144. Its totient is φ = 19435520.

The previous prime is 81730763. The next prime is 81730771. The reversal of 81730770 is 7703718.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (81730771) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 15154 + ... + 19826.

It is an arithmetic number, because the mean of its divisors is an integer number (3407346).

Almost surely, 2^81730770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81730770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109035072).

81730770 is an abundant number, since it is smaller than the sum of its proper divisors (136339374).

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

81730770 is a wasteful number, since it uses less digits than its factorization.

81730770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4747.

The product of its (nonzero) digits is 8232, while the sum is 33.

The square root of 81730770 is about 9040.5071760383. The cubic root of 81730770 is about 433.9721537770.

The spelling of 81730770 in words is "eighty-one million, seven hundred thirty thousand, seven hundred seventy".