21344043437 has 2 divisors, whose sum is σ = 21344043438. Its totient is φ = 21344043436.

The previous prime is 21344043389. The next prime is 21344043449. The reversal of 21344043437 is 73434044312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14624306761 + 6719736676 = 120931^2 + 81974^2 .

It is a cyclic number.

It is not a de Polignac number, because 21344043437 - 2¹⁶ = 21343977901 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21344043397 and 21344043406.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21344003437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10672021718 + 10672021719.

It is an arithmetic number, because the mean of its divisors is an integer number (10672021719).

Almost surely, 2^21344043437 is an apocalyptic number.

It is an amenable number.

21344043437 is a deficient number, since it is larger than the sum of its proper divisors (1).

21344043437 is an equidigital number, since it uses as much as digits as its factorization.

21344043437 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 96768, while the sum is 35.

Adding to 21344043437 its reverse (73434044312), we get a palindrome (94778087749).

The spelling of 21344043437 in words is "twenty-one billion, three hundred forty-four million, forty-three thousand, four hundred thirty-seven".