216403 has 8 divisors (see below), whose sum is σ = 239616. Its totient is φ = 193800.

The previous prime is 216401. The next prime is 216421. The reversal of 216403 is 304612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 216403 - 2¹ = 216401 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216401) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1038 + ... + 1228.

It is an arithmetic number, because the mean of its divisors is an integer number (29952).

2²¹⁶⁴⁰³ is an apocalyptic number.

216403 is a deficient number, since it is larger than the sum of its proper divisors (23213).

216403 is a wasteful number, since it uses less digits than its factorization.

216403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 216403 is about 465.1913584752. The cubic root of 216403 is about 60.0372916322.

Subtracting 216403 from its reverse (304612), we obtain a square (88209 = 297²).

The spelling of 216403 in words is "two hundred sixteen thousand, four hundred three".