21043542437 has 2 divisors, whose sum is σ = 21043542438. Its totient is φ = 21043542436.

The previous prime is 21043542427. The next prime is 21043542439. The reversal of 21043542437 is 73424534012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18677595556 + 2365946881 = 136666^2 + 48641^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043542437 - 2¹⁶ = 21043476901 is a prime.

Together with 21043542439, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21043542397 and 21043542406.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043542439) 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, 10521771218 + 10521771219.

It is an arithmetic number, because the mean of its divisors is an integer number (10521771219).

Almost surely, 2^21043542437 is an apocalyptic number.

It is an amenable number.

21043542437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043542437 is an equidigital number, since it uses as much as digits as its factorization.

21043542437 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 80640, while the sum is 35.

The spelling of 21043542437 in words is "twenty-one billion, forty-three million, five hundred forty-two thousand, four hundred thirty-seven".