21021220212 has 48 divisors (see below), whose sum is σ = 49969483200. Its totient is φ = 6876071680.

The previous prime is 21021220201. The next prime is 21021220217. The reversal of 21021220212 is 21202212012.

It is a junction number, because it is equal to n+sod(n) for n = 21021220191 and 21021220200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021220217) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 376762 + ... + 428942.

It is an arithmetic number, because the mean of its divisors is an integer number (1041030900).

Almost surely, 2^21021220212 is an apocalyptic number.

It is an amenable number.

21021220212 is an abundant number, since it is smaller than the sum of its proper divisors (28948262988).

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

21021220212 is a wasteful number, since it uses less digits than its factorization.

21021220212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52816 (or 52814 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21021220212 its reverse (21202212012), we get a palindrome (42223432224).

The spelling of 21021220212 in words is "twenty-one billion, twenty-one million, two hundred twenty thousand, two hundred twelve".