21210211220 has 96 divisors (see below), whose sum is σ = 49501549440. Its totient is φ = 7569520640.

The previous prime is 21210211123. The next prime is 21210211289. The reversal of 21210211220 is 2211201212.

It is a junction number, because it is equal to n+sod(n) for n = 21210211195 and 21210211204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2678507 + ... + 2686413.

It is an arithmetic number, because the mean of its divisors is an integer number (515641140).

Almost surely, 2^21210211220 is an apocalyptic number.

21210211220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21210211220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24750774720).

21210211220 is an abundant number, since it is smaller than the sum of its proper divisors (28291338220).

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

21210211220 is a wasteful number, since it uses less digits than its factorization.

21210211220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8153 (or 8151 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21210211220 its reverse (2211201212), we get a palindrome (23421412432).

It can be divided in two parts, 212102 and 11220, that added together give a palindrome (223322).

The spelling of 21210211220 in words is "twenty-one billion, two hundred ten million, two hundred eleven thousand, two hundred twenty".