1209994991 has 2 divisors, whose sum is σ = 1209994992. Its totient is φ = 1209994990.

The previous prime is 1209994967. The next prime is 1209994997. The reversal of 1209994991 is 1994999021.

It is a strong prime.

It is an emirp because it is prime and its reverse (1994999021) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1209994991 - 2¹⁴ = 1209978607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1209994997) 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, 604997495 + 604997496.

It is an arithmetic number, because the mean of its divisors is an integer number (604997496).

Almost surely, 2^1209994991 is an apocalyptic number.

1209994991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1209994991 is an equidigital number, since it uses as much as digits as its factorization.

1209994991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 472392, while the sum is 53.

The square root of 1209994991 is about 34784.9822624649. The cubic root of 1209994991 is about 1065.6007663509.

The spelling of 1209994991 in words is "one billion, two hundred nine million, nine hundred ninety-four thousand, nine hundred ninety-one".