81845903 has 4 divisors (see below), whose sum is σ = 81906888. Its totient is φ = 81784920.

The previous prime is 81845873. The next prime is 81845923. The reversal of 81845903 is 30954818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30954818 = 2 ⋅15477409.

It is a cyclic number.

It is not a de Polignac number, because 81845903 - 2¹² = 81841807 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81845923) 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, 28433 + ... + 31178.

It is an arithmetic number, because the mean of its divisors is an integer number (20476722).

Almost surely, 2^81845903 is an apocalyptic number.

81845903 is a deficient number, since it is larger than the sum of its proper divisors (60985).

81845903 is a wasteful number, since it uses less digits than its factorization.

81845903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60984.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 81845903 is about 9046.8725535403. The cubic root of 81845903 is about 434.1758350135.

The spelling of 81845903 in words is "eighty-one million, eight hundred forty-five thousand, nine hundred three".