1320000991 has 2 divisors, whose sum is σ = 1320000992. Its totient is φ = 1320000990.

The previous prime is 1320000943. The next prime is 1320001013. The reversal of 1320000991 is 1990000231.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1320000991 - 2¹¹ = 1319998943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1320000901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660000495 + 660000496.

It is an arithmetic number, because the mean of its divisors is an integer number (660000496).

Almost surely, 2^1320000991 is an apocalyptic number.

1320000991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1320000991 is an equidigital number, since it uses as much as digits as its factorization.

1320000991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 1320000991 is about 36331.8178873560. The cubic root of 1320000991 is about 1096.9615850038.

The spelling of 1320000991 in words is "one billion, three hundred twenty million, nine hundred ninety-one", and thus it is an aban number.