1289863891 has 2 divisors, whose sum is σ = 1289863892. Its totient is φ = 1289863890.

The previous prime is 1289863879. The next prime is 1289863951. The reversal of 1289863891 is 1983689821.

It is a weak prime.

It is an emirp because it is prime and its reverse (1983689821) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1289863891 - 2¹⁹ = 1289339603 is a prime.

It is not a weakly prime, because it can be changed into another prime (1289363891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 644931945 + 644931946.

It is an arithmetic number, because the mean of its divisors is an integer number (644931946).

Almost surely, 2^1289863891 is an apocalyptic number.

1289863891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1289863891 is an equidigital number, since it uses as much as digits as its factorization.

1289863891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1492992, while the sum is 55.

The square root of 1289863891 is about 35914.6751481898. The cubic root of 1289863891 is about 1088.5489461839.

The spelling of 1289863891 in words is "one billion, two hundred eighty-nine million, eight hundred sixty-three thousand, eight hundred ninety-one".