1288219721 has 2 divisors, whose sum is σ = 1288219722. Its totient is φ = 1288219720.

The previous prime is 1288219687. The next prime is 1288219733. The reversal of 1288219721 is 1279128821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 922033225 + 366186496 = 30365^2 + 19136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1288219721 - 2⁶ = 1288219657 is a prime.

It is not a weakly prime, because it can be changed into another prime (1288219771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 644109860 + 644109861.

It is an arithmetic number, because the mean of its divisors is an integer number (644109861).

Almost surely, 2^1288219721 is an apocalyptic number.

It is an amenable number.

1288219721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1288219721 is an equidigital number, since it uses as much as digits as its factorization.

1288219721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 41.

The square root of 1288219721 is about 35891.7779024667. Note that the first 3 decimals coincide. The cubic root of 1288219721 is about 1088.0862305615.

The spelling of 1288219721 in words is "one billion, two hundred eighty-eight million, two hundred nineteen thousand, seven hundred twenty-one".