1564336721 has 2 divisors, whose sum is σ = 1564336722. Its totient is φ = 1564336720.

The previous prime is 1564336693. The next prime is 1564336723. The reversal of 1564336721 is 1276334651.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1556697025 + 7639696 = 39455^2 + 2764^2 .

It is a cyclic number.

It is not a de Polignac number, because 1564336721 - 2¹⁰ = 1564335697 is a prime.

Together with 1564336723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1564336723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 782168360 + 782168361.

It is an arithmetic number, because the mean of its divisors is an integer number (782168361).

Almost surely, 2^1564336721 is an apocalyptic number.

It is an amenable number.

1564336721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1564336721 is an equidigital number, since it uses as much as digits as its factorization.

1564336721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 38.

The square root of 1564336721 is about 39551.6968156867. The cubic root of 1564336721 is about 1160.8517132225.

The spelling of 1564336721 in words is "one billion, five hundred sixty-four million, three hundred thirty-six thousand, seven hundred twenty-one".