81793858 has 4 divisors (see below), whose sum is σ = 122690790. Its totient is φ = 40896928.

The previous prime is 81793853. The next prime is 81793861. The reversal of 81793858 is 85839718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 53246209 + 28547649 = 7297^2 + 5343^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81793853) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20448463 + ... + 20448466.

Almost surely, 2^81793858 is an apocalyptic number.

81793858 is a deficient number, since it is larger than the sum of its proper divisors (40896932).

81793858 is a wasteful number, since it uses less digits than its factorization.

81793858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40896931.

The product of its digits is 483840, while the sum is 49.

The square root of 81793858 is about 9043.9956877478. The cubic root of 81793858 is about 434.0837861270.

The spelling of 81793858 in words is "eighty-one million, seven hundred ninety-three thousand, eight hundred fifty-eight".