1281944561 has 2 divisors, whose sum is σ = 1281944562. Its totient is φ = 1281944560.

The previous prime is 1281944539. The next prime is 1281944603. The reversal of 1281944561 is 1654491821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1070532961 + 211411600 = 32719^2 + 14540^2 .

It is a cyclic number.

It is not a de Polignac number, because 1281944561 - 2¹⁴ = 1281928177 is a prime.

It is not a weakly prime, because it can be changed into another prime (1281941561) 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, 640972280 + 640972281.

It is an arithmetic number, because the mean of its divisors is an integer number (640972281).

Almost surely, 2^1281944561 is an apocalyptic number.

It is an amenable number.

1281944561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1281944561 is an equidigital number, since it uses as much as digits as its factorization.

1281944561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69120, while the sum is 41.

The square root of 1281944561 is about 35804.2533925789. The cubic root of 1281944561 is about 1086.3165966330.

The spelling of 1281944561 in words is "one billion, two hundred eighty-one million, nine hundred forty-four thousand, five hundred sixty-one".