1328833721 has 2 divisors, whose sum is σ = 1328833722. Its totient is φ = 1328833720.

The previous prime is 1328833691. The next prime is 1328833729. The reversal of 1328833721 is 1273388231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 856206121 + 472627600 = 29261^2 + 21740^2 .

It is a cyclic number.

It is not a de Polignac number, because 1328833721 - 2²² = 1324639417 is a prime.

It is not a weakly prime, because it can be changed into another prime (1328833729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 664416860 + 664416861.

It is an arithmetic number, because the mean of its divisors is an integer number (664416861).

Almost surely, 2^1328833721 is an apocalyptic number.

It is an amenable number.

1328833721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1328833721 is an equidigital number, since it uses as much as digits as its factorization.

1328833721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 38.

The square root of 1328833721 is about 36453.1716178442. The cubic root of 1328833721 is about 1099.4029048728.

The spelling of 1328833721 in words is "one billion, three hundred twenty-eight million, eight hundred thirty-three thousand, seven hundred twenty-one".