21231113213 has 4 divisors (see below), whose sum is σ = 21231865020. Its totient is φ = 21230361408.

The previous prime is 21231113159. The next prime is 21231113231. The reversal of 21231113213 is 31231113212.

It is a happy number.

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 13124451844 + 8106661369 = 114562^2 + 90037^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231113213 - 2⁶ = 21231113149 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 (21231113273) 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, 331820 + ... + 390597.

It is an arithmetic number, because the mean of its divisors is an integer number (5307966255).

Almost surely, 2^21231113213 is an apocalyptic number.

It is an amenable number.

21231113213 is a deficient number, since it is larger than the sum of its proper divisors (751807).

21231113213 is an equidigital number, since it uses as much as digits as its factorization.

21231113213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 751806.

The product of its digits is 216, while the sum is 20.

Adding to 21231113213 its reverse (31231113212), we get a palindrome (52462226425).

Subtracting 21231113213 from its reverse (31231113212), we obtain a palindrome (9999999999).

The spelling of 21231113213 in words is "twenty-one billion, two hundred thirty-one million, one hundred thirteen thousand, two hundred thirteen".