21220232220 has 432 divisors, whose sum is σ = 74537438976. Its totient is φ = 4876185600.

The previous prime is 21220232191. The next prime is 21220232221. The reversal of 21220232220 is 2223202212.

21220232220 is a `hidden beast` number, since 212 + 2 + 0 + 232 + 220 = 666.

It is a super-2 number, since 2×21220232220² (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 = 21220232193 and 21220232202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220232221) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 35784244 + ... + 35784836.

It is an arithmetic number, because the mean of its divisors is an integer number (172540368).

Almost surely, 2^21220232220 is an apocalyptic number.

21220232220 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 21220232220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37268719488).

21220232220 is an abundant number, since it is smaller than the sum of its proper divisors (53317206756).

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

21220232220 is a wasteful number, since it uses less digits than its factorization.

21220232220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714 (or 698 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

Adding to 21220232220 its reverse (2223202212), we get a palindrome (23443434432).

The spelling of 21220232220 in words is "twenty-one billion, two hundred twenty million, two hundred thirty-two thousand, two hundred twenty".