1296126721 has 2 divisors, whose sum is σ = 1296126722. Its totient is φ = 1296126720.

The previous prime is 1296126703. The next prime is 1296126731. The reversal of 1296126721 is 1276216921.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1291396096 + 4730625 = 35936^2 + 2175^2 .

It is a cyclic number.

It is not a de Polignac number, because 1296126721 - 2⁷ = 1296126593 is a prime.

It is not a weakly prime, because it can be changed into another prime (1296126731) 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, 648063360 + 648063361.

It is an arithmetic number, because the mean of its divisors is an integer number (648063361).

Almost surely, 2^1296126721 is an apocalyptic number.

It is an amenable number.

1296126721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1296126721 is an equidigital number, since it uses as much as digits as its factorization.

1296126721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 1296126721 is about 36001.7599708681. The cubic root of 1296126721 is about 1090.3078896243.

The spelling of 1296126721 in words is "one billion, two hundred ninety-six million, one hundred twenty-six thousand, seven hundred twenty-one".