216406 has 4 divisors (see below), whose sum is σ = 324612. Its totient is φ = 108202.

The previous prime is 216401. The next prime is 216421. The reversal of 216406 is 604612.

It is a semiprime because it is the product of two primes.

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 as a sum of consecutive naturals, namely, 54100 + ... + 54103.

It is an arithmetic number, because the mean of its divisors is an integer number (81153).

2²¹⁶⁴⁰⁶ is an apocalyptic number.

216406 is a deficient number, since it is larger than the sum of its proper divisors (108206).

216406 is a wasteful number, since it uses less digits than its factorization.

216406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108205.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 216406 is about 465.1945829435. The cubic root of 216406 is about 60.0375690638.

The spelling of 216406 in words is "two hundred sixteen thousand, four hundred six".