1723621 has 2 divisors, whose sum is σ = 1723622. Its totient is φ = 1723620.

The previous prime is 1723619. The next prime is 1723627. The reversal of 1723621 is 1263271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1718721 + 4900 = 1311^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 1723621 - 2¹ = 1723619 is a prime.

Together with 1723619, it forms a pair of twin primes.

1723621 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1723592 and 1723601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1723627) 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 as a sum of consecutive naturals, namely, 861810 + 861811.

It is an arithmetic number, because the mean of its divisors is an integer number (861811).

2^1723621 is an apocalyptic number.

It is an amenable number.

1723621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1723621 is an equidigital number, since it uses as much as digits as its factorization.

1723621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 504, while the sum is 22.

The square root of 1723621 is about 1312.8674723673. The cubic root of 1723621 is about 119.8985485134.

Adding to 1723621 its reverse (1263271), we get a palindrome (2986892).

The spelling of 1723621 in words is "one million, seven hundred twenty-three thousand, six hundred twenty-one".