21180391543 has 2 divisors, whose sum is σ = 21180391544. Its totient is φ = 21180391542.

The previous prime is 21180391517. The next prime is 21180391553. The reversal of 21180391543 is 34519308112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21180391543 - 2⁹ = 21180391031 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21180391553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10590195771 + 10590195772.

It is an arithmetic number, because the mean of its divisors is an integer number (10590195772).

Almost surely, 2^21180391543 is an apocalyptic number.

21180391543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21180391543 is an equidigital number, since it uses as much as digits as its factorization.

21180391543 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 37.

Adding to 21180391543 its reverse (34519308112), we get a palindrome (55699699655).

The spelling of 21180391543 in words is "twenty-one billion, one hundred eighty million, three hundred ninety-one thousand, five hundred forty-three".