1205478991 has 2 divisors, whose sum is σ = 1205478992. Its totient is φ = 1205478990.

The previous prime is 1205478971. The next prime is 1205479001. The reversal of 1205478991 is 1998745021.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1205478991 - 2¹⁵ = 1205446223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1205478971) 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, 602739495 + 602739496.

It is an arithmetic number, because the mean of its divisors is an integer number (602739496).

Almost surely, 2^1205478991 is an apocalyptic number.

1205478991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1205478991 is an equidigital number, since it uses as much as digits as its factorization.

1205478991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 46.

The square root of 1205478991 is about 34720.0085109437. The cubic root of 1205478991 is about 1064.2734186126.

The spelling of 1205478991 in words is "one billion, two hundred five million, four hundred seventy-eight thousand, nine hundred ninety-one".