21212121213 has 8 divisors (see below), whose sum is σ = 31425364800. Its totient is φ = 14141414124.

The previous prime is 21212121209. The next prime is 21212121283. The reversal of 21212121213 is 31212121212.

It is not a de Polignac number, because 21212121213 - 2² = 21212121209 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212121283) 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, 392817033 + ... + 392817086.

It is an arithmetic number, because the mean of its divisors is an integer number (3928170600).

Almost surely, 2^21212121213 is an apocalyptic number.

It is an amenable number.

21212121213 is a deficient number, since it is larger than the sum of its proper divisors (10213243587).

21212121213 is an equidigital number, since it uses as much as digits as its factorization.

21212121213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 785634128 (or 785634122 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

Adding to 21212121213 its reverse (31212121212), we get a palindrome (52424242425).

Subtracting 21212121213 from its reverse (31212121212), we obtain a palindrome (9999999999).

The spelling of 21212121213 in words is "twenty-one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred thirteen".