1722221 has 4 divisors (see below), whose sum is σ = 1758912. Its totient is φ = 1685532.

The previous prime is 1722211. The next prime is 1722241. The reversal of 1722221 is 1222271.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1722221 - 2¹⁰ = 1721197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1722221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1722211) 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, 18275 + ... + 18368.

It is an arithmetic number, because the mean of its divisors is an integer number (439728).

2^1722221 is an apocalyptic number.

It is an amenable number.

1722221 is a deficient number, since it is larger than the sum of its proper divisors (36691).

1722221 is an equidigital number, since it uses as much as digits as its factorization.

1722221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36690.

The product of its digits is 112, while the sum is 17.

The square root of 1722221 is about 1312.3341800014. The cubic root of 1722221 is about 119.8660774470.

Adding to 1722221 its reverse (1222271), we get a palindrome (2944492).

The spelling of 1722221 in words is "one million, seven hundred twenty-two thousand, two hundred twenty-one".