81993673 has 8 divisors (see below), whose sum is σ = 83353896. Its totient is φ = 80640000.

The previous prime is 81993661. The next prime is 81993677. The reversal of 81993673 is 37639918.

It can be written as a sum of positive squares in 4 ways, for example, as 40106889 + 41886784 = 6333^2 + 6472^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81993673 - 2⁵ = 81993641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81993677) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27873 + ... + 30673.

It is an arithmetic number, because the mean of its divisors is an integer number (10419237).

Almost surely, 2^81993673 is an apocalyptic number.

It is an amenable number.

81993673 is a deficient number, since it is larger than the sum of its proper divisors (1360223).

81993673 is a wasteful number, since it uses less digits than its factorization.

81993673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3275.

The product of its digits is 244944, while the sum is 46.

The square root of 81993673 is about 9055.0357812656. The cubic root of 81993673 is about 434.4369744950.

The spelling of 81993673 in words is "eighty-one million, nine hundred ninety-three thousand, six hundred seventy-three".