9991543 has 2 divisors, whose sum is σ = 9991544. Its totient is φ = 9991542.

The previous prime is 9991489. The next prime is 9991559. The reversal of 9991543 is 3451999.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9991543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 9991496 and 9991505.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9991343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995771 + 4995772.

It is an arithmetic number, because the mean of its divisors is an integer number (4995772).

Almost surely, 2^9991543 is an apocalyptic number.

9991543 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991543 is an equidigital number, since it uses as much as digits as its factorization.

9991543 is an evil number, because the sum of its binary digits is even.

The product of its digits is 43740, while the sum is 40.

The square root of 9991543 is about 3160.9402082292. The cubic root of 9991543 is about 215.3827183605.

The spelling of 9991543 in words is "nine million, nine hundred ninety-one thousand, five hundred forty-three".