221405 has 4 divisors (see below), whose sum is σ = 265692. Its totient is φ = 177120.

The previous prime is 221401. The next prime is 221411. The reversal of 221405 is 504122.

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

It can be written as a sum of positive squares in 2 ways, for example, as 63001 + 158404 = 251^2 + 398^2 .

It is not a de Polignac number, because 221405 - 2² = 221401 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221405.

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, 22136 + ... + 22145.

It is an arithmetic number, because the mean of its divisors is an integer number (66423).

2²²¹⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

221405 is a deficient number, since it is larger than the sum of its proper divisors (44287).

221405 is an equidigital number, since it uses as much as digits as its factorization.

221405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44286.

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 221405 is about 470.5369273500. The cubic root of 221405 is about 60.4963456573.

Adding to 221405 its reverse (504122), we get a palindrome (725527).

It can be divided in two parts, 221 and 405, that added together give a palindrome (626).

The spelling of 221405 in words is "two hundred twenty-one thousand, four hundred five".