21213343447 has 2 divisors, whose sum is σ = 21213343448. Its totient is φ = 21213343446.

The previous prime is 21213343367. The next prime is 21213343457. The reversal of 21213343447 is 74434331212.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21213343447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21213343457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606671723 + 10606671724.

It is an arithmetic number, because the mean of its divisors is an integer number (10606671724).

Almost surely, 2^21213343447 is an apocalyptic number.

21213343447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213343447 is an equidigital number, since it uses as much as digits as its factorization.

21213343447 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 34.

Adding to 21213343447 its reverse (74434331212), we get a palindrome (95647674659).

The spelling of 21213343447 in words is "twenty-one billion, two hundred thirteen million, three hundred forty-three thousand, four hundred forty-seven".