1543440991 has 2 divisors, whose sum is σ = 1543440992. Its totient is φ = 1543440990.

The previous prime is 1543440961. The next prime is 1543441007. The reversal of 1543440991 is 1990443451.

It is a strong prime.

It is an emirp because it is prime and its reverse (1990443451) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1543440991 - 2¹⁷ = 1543309919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1543440961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 771720495 + 771720496.

It is an arithmetic number, because the mean of its divisors is an integer number (771720496).

Almost surely, 2^1543440991 is an apocalyptic number.

1543440991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1543440991 is an equidigital number, since it uses as much as digits as its factorization.

1543440991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 40.

The square root of 1543440991 is about 39286.6515625855. The cubic root of 1543440991 is about 1155.6598095313.

The spelling of 1543440991 in words is "one billion, five hundred forty-three million, four hundred forty thousand, nine hundred ninety-one".