81812903 has 4 divisors (see below), whose sum is σ = 81831120. Its totient is φ = 81794688.

The previous prime is 81812897. The next prime is 81812921. The reversal of 81812903 is 30921818.

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

It is a cyclic number.

It is not a de Polignac number, because 81812903 - 2⁶ = 81812839 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81812903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81812933) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2951 + ... + 13127.

It is an arithmetic number, because the mean of its divisors is an integer number (20457780).

Almost surely, 2^81812903 is an apocalyptic number.

81812903 is a deficient number, since it is larger than the sum of its proper divisors (18217).

81812903 is a wasteful number, since it uses less digits than its factorization.

81812903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18216.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 81812903 is about 9045.0485349720. The cubic root of 81812903 is about 434.1174744110.

The spelling of 81812903 in words is "eighty-one million, eight hundred twelve thousand, nine hundred three".