221705 has 16 divisors (see below), whose sum is σ = 302400. Its totient is φ = 154560.

The previous prime is 221677. The next prime is 221707. The reversal of 221705 is 507122.

It is not a de Polignac number, because 221705 - 2¹⁰ = 220681 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1526 + ... + 1664.

It is an arithmetic number, because the mean of its divisors is an integer number (18900).

2²²¹⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

221705 is a deficient number, since it is larger than the sum of its proper divisors (80695).

221705 is a wasteful number, since it uses less digits than its factorization.

221705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184.

The product of its (nonzero) digits is 140, while the sum is 17.

The square root of 221705 is about 470.8556041930. The cubic root of 221705 is about 60.5236571644.

Adding to 221705 its reverse (507122), we get a palindrome (728827).

The spelling of 221705 in words is "two hundred twenty-one thousand, seven hundred five".