1722721 has 16 divisors (see below), whose sum is σ = 2314368. Its totient is φ = 1238400.

The previous prime is 1722719. The next prime is 1722731. The reversal of 1722721 is 1272271.

It is a cyclic number.

It is not a de Polignac number, because 1722721 - 2¹ = 1722719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1722692 and 1722701.

It is not an unprimeable number, because it can be changed into a prime (1722731) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 141 + ... + 1861.

It is an arithmetic number, because the mean of its divisors is an integer number (144648).

2^1722721 is an apocalyptic number.

1722721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1722721 is a deficient number, since it is larger than the sum of its proper divisors (591647).

1722721 is a wasteful number, since it uses less digits than its factorization.

1722721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1752.

The product of its digits is 392, while the sum is 22.

The square root of 1722721 is about 1312.5246664349. The cubic root of 1722721 is about 119.8776762758.

Adding to 1722721 its reverse (1272271), we get a palindrome (2994992).

The spelling of 1722721 in words is "one million, seven hundred twenty-two thousand, seven hundred twenty-one".