1267991489 has 2 divisors, whose sum is σ = 1267991490. Its totient is φ = 1267991488.

The previous prime is 1267991423. The next prime is 1267991497. The reversal of 1267991489 is 9841997621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 891321025 + 376670464 = 29855^2 + 19408^2 .

It is a cyclic number.

It is not a de Polignac number, because 1267991489 - 2²⁰ = 1266942913 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1267991089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 633995744 + 633995745.

It is an arithmetic number, because the mean of its divisors is an integer number (633995745).

Almost surely, 2^1267991489 is an apocalyptic number.

It is an amenable number.

1267991489 is a deficient number, since it is larger than the sum of its proper divisors (1).

1267991489 is an equidigital number, since it uses as much as digits as its factorization.

1267991489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 56.

The square root of 1267991489 is about 35608.8681229831. The cubic root of 1267991489 is about 1082.3609441855.

The spelling of 1267991489 in words is "one billion, two hundred sixty-seven million, nine hundred ninety-one thousand, four hundred eighty-nine".