1719721 has 2 divisors, whose sum is σ = 1719722. Its totient is φ = 1719720.

The previous prime is 1719719. The next prime is 1719743. The reversal of 1719721 is 1279171.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1590121 + 129600 = 1261^2 + 360^2 .

It is an emirp because it is prime and its reverse (1279171) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1719721 - 2¹ = 1719719 is a prime.

Together with 1719719, it forms a pair of twin primes.

1719721 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1719721.

It is not a weakly prime, because it can be changed into another prime (1719701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 859860 + 859861.

It is an arithmetic number, because the mean of its divisors is an integer number (859861).

2^1719721 is an apocalyptic number.

It is an amenable number.

1719721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1719721 is an equidigital number, since it uses as much as digits as its factorization.

1719721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 882, while the sum is 28.

The square root of 1719721 is about 1311.3813327938. The cubic root of 1719721 is about 119.8080496039.

The spelling of 1719721 in words is "one million, seven hundred nineteen thousand, seven hundred twenty-one".