81809730 has 32 divisors (see below), whose sum is σ = 218160000. Its totient is φ = 21815856.

The previous prime is 81809711. The next prime is 81809743. The reversal of 81809730 is 3790818.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 151230 + ... + 151769.

It is an arithmetic number, because the mean of its divisors is an integer number (6817500).

Almost surely, 2^81809730 is an apocalyptic number.

81809730 is an abundant number, since it is smaller than the sum of its proper divisors (136350270).

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

81809730 is a wasteful number, since it uses less digits than its factorization.

81809730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303015 (or 303009 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 36.

The square root of 81809730 is about 9044.8731334386. The cubic root of 81809730 is about 434.1118621237. Note that the first 3 decimals are identical.

The spelling of 81809730 in words is "eighty-one million, eight hundred nine thousand, seven hundred thirty".