21122222220 has 216 divisors, whose sum is σ = 74568809952. Its totient is φ = 4819246080.

The previous prime is 21122222207. The next prime is 21122222243. The reversal of 21122222220 is 2222222112.

It is a super-2 number, since 2×21122222220² (a number of 21 digits) contains 22 as substring.

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 = 21122222193 and 21122222202.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 341737 + ... + 398783.

It is an arithmetic number, because the mean of its divisors is an integer number (345225972).

Almost surely, 2^21122222220 is an apocalyptic number.

21122222220 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 21122222220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37284404976).

21122222220 is an abundant number, since it is smaller than the sum of its proper divisors (53446587732).

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

21122222220 is a wasteful number, since it uses less digits than its factorization.

21122222220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57101 (or 57085 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

Adding to 21122222220 its reverse (2222222112), we get a palindrome (23344444332).

It can be divided in two parts, 21122 and 222220, that added together give a palindrome (243342).

The spelling of 21122222220 in words is "twenty-one billion, one hundred twenty-two million, two hundred twenty-two thousand, two hundred twenty".