21243034213 has 4 divisors (see below), whose sum is σ = 21244751980. Its totient is φ = 21241316448.

The previous prime is 21243034147. The next prime is 21243034223. The reversal of 21243034213 is 31243034212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18424804644 + 2818229569 = 135738^2 + 53087^2 .

It is a cyclic number.

It is not a de Polignac number, because 21243034213 - 2⁹ = 21243033701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243034223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 840198 + ... + 865111.

It is an arithmetic number, because the mean of its divisors is an integer number (5311187995).

Almost surely, 2^21243034213 is an apocalyptic number.

It is an amenable number.

21243034213 is a deficient number, since it is larger than the sum of its proper divisors (1717767).

21243034213 is a wasteful number, since it uses less digits than its factorization.

21243034213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1717766.

The product of its (nonzero) digits is 3456, while the sum is 25.

Adding to 21243034213 its reverse (31243034212), we get a palindrome (52486068425).

Subtracting 21243034213 from its reverse (31243034212), we obtain a palindrome (9999999999).

The spelling of 21243034213 in words is "twenty-one billion, two hundred forty-three million, thirty-four thousand, two hundred thirteen".