221001 has 16 divisors (see below), whose sum is σ = 331968. Its totient is φ = 129600.

The previous prime is 220973. The next prime is 221021. The reversal of 221001 is 100122.

It is a happy number.

It is not a de Polignac number, because 221001 - 2⁷ = 220873 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1131 + ... + 1311.

It is an arithmetic number, because the mean of its divisors is an integer number (20748).

2²²¹⁰⁰¹ is an apocalyptic number.

It is an amenable number.

221001 is a deficient number, since it is larger than the sum of its proper divisors (110967).

221001 is a wasteful number, since it uses less digits than its factorization.

221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232.

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 221001 is about 470.1074345296. The cubic root of 221001 is about 60.4595271507.

Adding to 221001 its reverse (100122), we get a palindrome (321123).

It can be divided in two parts, 22 and 1001, that multiplied together give a palindrome (22022).

The spelling of 221001 in words is "two hundred twenty-one thousand, one", and thus it is an iban number.