21247911943 has 2 divisors, whose sum is σ = 21247911944. Its totient is φ = 21247911942.

The previous prime is 21247911929. The next prime is 21247912031. The reversal of 21247911943 is 34911974212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21247911943 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21247911943.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21247911143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10623955971 + 10623955972.

It is an arithmetic number, because the mean of its divisors is an integer number (10623955972).

Almost surely, 2^21247911943 is an apocalyptic number.

21247911943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21247911943 is an equidigital number, since it uses as much as digits as its factorization.

21247911943 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 43.

It can be divided in two parts, 212479 and 11943, that added together give a palindrome (224422).

The spelling of 21247911943 in words is "twenty-one billion, two hundred forty-seven million, nine hundred eleven thousand, nine hundred forty-three".