21212021213 has 8 divisors (see below), whose sum is σ = 21455416440. Its totient is φ = 20968738560.

The previous prime is 21212021161. The next prime is 21212021221. The reversal of 21212021213 is 31212021212.

It can be written as a sum of positive squares in 4 ways, for example, as 652189444 + 20559831769 = 25538^2 + 143387^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212021213 - 2³⁰ = 20138279389 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212021191 and 21212021200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212023213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 385481 + ... + 437057.

It is an arithmetic number, because the mean of its divisors is an integer number (2681927055).

Almost surely, 2^21212021213 is an apocalyptic number.

It is an amenable number.

21212021213 is a deficient number, since it is larger than the sum of its proper divisors (243395227).

21212021213 is an equidigital number, since it uses as much as digits as its factorization.

21212021213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56287.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21212021213 its reverse (31212021212), we get a palindrome (52424042425).

Subtracting 21212021213 from its reverse (31212021212), we obtain a palindrome (9999999999).

The spelling of 21212021213 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, two hundred thirteen".