21311020212 has 12 divisors (see below), whose sum is σ = 49725713856. Its totient is φ = 7103673400.

The previous prime is 21311020189. The next prime is 21311020219. The reversal of 21311020212 is 21202011312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21311020191 and 21311020200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311020219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 887959164 + ... + 887959187.

It is an arithmetic number, because the mean of its divisors is an integer number (4143809488).

Almost surely, 2^21311020212 is an apocalyptic number.

It is an amenable number.

21311020212 is an abundant number, since it is smaller than the sum of its proper divisors (28414693644).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21311020212 is a wasteful number, since it uses less digits than its factorization.

21311020212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1775918358 (or 1775918356 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21311020212 its reverse (21202011312), we get a palindrome (42513031524).

The spelling of 21311020212 in words is "twenty-one billion, three hundred eleven million, twenty thousand, two hundred twelve".