221406 has 8 divisors (see below), whose sum is σ = 442824. Its totient is φ = 73800.

The previous prime is 221401. The next prime is 221411. The reversal of 221406 is 604122.

It is an interprime number because it is at equal distance from previous prime (221401) and next prime (221411).

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

221406 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221401) 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, 18445 + ... + 18456.

It is an arithmetic number, because the mean of its divisors is an integer number (55353).

2²²¹⁴⁰⁶ is an apocalyptic number.

221406 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221406 is a wasteful number, since it uses less digits than its factorization.

221406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36906.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 221406 is about 470.5379899647. The cubic root of 221406 is about 60.4964367366.

Adding to 221406 its reverse (604122), we get a palindrome (825528).

The spelling of 221406 in words is "two hundred twenty-one thousand, four hundred six".