21212312213 has 8 divisors (see below), whose sum is σ = 21306488280. Its totient is φ = 21118187520.

The previous prime is 21212312171. The next prime is 21212312273. The reversal of 21212312213 is 31221321212.

It can be written as a sum of positive squares in 4 ways, for example, as 13778768689 + 7433543524 = 117383^2 + 86218^2 .

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 21212312213 - 2¹⁶ = 21212246677 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 (21212312273) 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, 984431 + ... + 1005747.

It is an arithmetic number, because the mean of its divisors is an integer number (2663311035).

Almost surely, 2^21212312213 is an apocalyptic number.

It is an amenable number.

21212312213 is a deficient number, since it is larger than the sum of its proper divisors (94176067).

21212312213 is a wasteful number, since it uses less digits than its factorization.

21212312213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25687.

The product of its digits is 288, while the sum is 20.

Adding to 21212312213 its reverse (31221321212), we get a palindrome (52433633425).

The spelling of 21212312213 in words is "twenty-one billion, two hundred twelve million, three hundred twelve thousand, two hundred thirteen".