81003 has 16 divisors (see below), whose sum is σ = 121856. Its totient is φ = 47520.

The previous prime is 81001. The next prime is 81013. The reversal of 81003 is 30018.

81003 is a nontrivial binomial coefficient, being equal to C(403, 2).

It is not a de Polignac number, because 81003 - 2¹ = 81001 is a prime.

It is a super-2 number, since 2×81003² = 13122972018, which contains 22 as substring.

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 81003.

It is not an unprimeable number, because it can be changed into a prime (81001) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1176 + ... + 1242.

It is an arithmetic number, because the mean of its divisors is an integer number (7616).

2⁸¹⁰⁰³ is an apocalyptic number.

81003 is the 402-nd triangular number.

81003 is a deficient number, since it is larger than the sum of its proper divisors (40853).

81003 is a wasteful number, since it uses less digits than its factorization.

81003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 81003 is about 284.6102598291. The cubic root of 81003 is about 43.2680212691.

The spelling of 81003 in words is "eighty-one thousand, three".