21212213220 has 288 divisors, whose sum is σ = 75230588160. Its totient is φ = 4785454080.

The previous prime is 21212213219. The next prime is 21212213251. The reversal of 21212213220 is 2231221212.

21212213220 is a `hidden beast` number, since 2 + 121 + 221 + 322 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21212213193 and 21212213202.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1678686 + ... + 1691274.

It is an arithmetic number, because the mean of its divisors is an integer number (261217320).

Almost surely, 2^21212213220 is an apocalyptic number.

21212213220 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 21212213220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37615294080).

21212213220 is an abundant number, since it is smaller than the sum of its proper divisors (54018374940).

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

21212213220 is a wasteful number, since it uses less digits than its factorization.

21212213220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12675 (or 12670 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21212213220 its reverse (2231221212), we get a palindrome (23443434432).

It can be divided in two parts, 21212 and 213220, that added together give a palindrome (234432).

The spelling of 21212213220 in words is "twenty-one billion, two hundred twelve million, two hundred thirteen thousand, two hundred twenty".