16403 has 4 divisors (see below), whose sum is σ = 16800.
Its totient is φ = 16008.
The previous prime is 16381. The next prime is 16411. The reversal of 16403 is 30461.
16403 is nontrivially palindromic in base 3.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 30461 = 83 ⋅367.
It is a cyclic number.
It is not a de Polignac number, because 16403 - 26 = 16339 is a prime.
It is a Duffinian number.
It is a plaindrome in base 9.
It is a nialpdrome in base 7.
It is not an unprimeable number, because it can be changed into a prime (16433) 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, 128 + ... + 221.
It is an arithmetic number, because the mean of its divisors is an integer number (4200).
216403 is an apocalyptic number.
16403 is a deficient number, since it is larger than the sum of its proper divisors (397).
16403 is an equidigital number, since it uses as much as digits as its factorization.
16403 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 396.
The product of its (nonzero) digits is 72, while the sum is 14.
The square root of 16403 is about 128.0741972452.
The cubic root of 16403 is about 25.4082309489.
Adding to 16403 its reverse (30461), we get a palindrome (46864).
The spelling of 16403 in words is "sixteen thousand, four hundred three".