1321729 has 2 divisors, whose sum is σ = 1321730. Its totient is φ = 1321728.

The previous prime is 1321711. The next prime is 1321753. The reversal of 1321729 is 9271231.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 859329 + 462400 = 927^2 + 680^2 .

It is a cyclic number.

It is not a de Polignac number, because 1321729 - 2⁷ = 1321601 is a prime.

It is not a weakly prime, because it can be changed into another prime (1321759) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660864 + 660865.

It is an arithmetic number, because the mean of its divisors is an integer number (660865).

2^1321729 is an apocalyptic number.

It is an amenable number.

1321729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321729 is an equidigital number, since it uses as much as digits as its factorization.

1321729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 756, while the sum is 25.

The square root of 1321729 is about 1149.6647337376. The cubic root of 1321729 is about 109.7440052558.

The spelling of 1321729 in words is "one million, three hundred twenty-one thousand, seven hundred twenty-nine".