816503 has 4 divisors (see below), whose sum is σ = 820008. Its totient is φ = 813000.

The previous prime is 816499. The next prime is 816521. The reversal of 816503 is 305618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 305618 = 2 ⋅152809.

It is a cyclic number.

It is not a de Polignac number, because 816503 - 2² = 816499 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816593) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1376 + ... + 1877.

It is an arithmetic number, because the mean of its divisors is an integer number (205002).

2⁸¹⁶⁵⁰³ is an apocalyptic number.

816503 is a deficient number, since it is larger than the sum of its proper divisors (3505).

816503 is a wasteful number, since it uses less digits than its factorization.

816503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3504.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 816503 is about 903.6055555385. The cubic root of 816503 is about 93.4657714512.

The spelling of 816503 in words is "eight hundred sixteen thousand, five hundred three".