21243340747 has 2 divisors, whose sum is σ = 21243340748. Its totient is φ = 21243340746.

The previous prime is 21243340717. The next prime is 21243340819. The reversal of 21243340747 is 74704334212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21243340747 is a prime.

It is not a weakly prime, because it can be changed into another prime (21243340717) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621670373 + 10621670374.

It is an arithmetic number, because the mean of its divisors is an integer number (10621670374).

Almost surely, 2^21243340747 is an apocalyptic number.

21243340747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243340747 is an equidigital number, since it uses as much as digits as its factorization.

21243340747 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 112896, while the sum is 37.

Adding to 21243340747 its reverse (74704334212), we get a palindrome (95947674959).

The spelling of 21243340747 in words is "twenty-one billion, two hundred forty-three million, three hundred forty thousand, seven hundred forty-seven".