21121222001220 has 288 divisors, whose sum is σ = 71221607009280. Its totient is φ = 5023246368000.

The previous prime is 21121222001179. The next prime is 21121222001221. The reversal of 21121222001220 is 2210022212112.

It is a happy number.

21121222001220 is a `hidden beast` number, since 2 + 11 + 212 + 220 + 0 + 1 + 220 = 666.

It is a super-2 number, since 2×21121222001220² (a number of 27 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 = 21121222001193 and 21121222001202.

It is not an unprimeable number, because it can be changed into a prime (21121222001221) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 57174505 + ... + 57542735.

It is an arithmetic number, because the mean of its divisors is an integer number (247297246560).

Almost surely, 2^{21121222001220} is an apocalyptic number.

21121222001220 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 21121222001220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35610803504640).

21121222001220 is an abundant number, since it is smaller than the sum of its proper divisors (50100385008060).

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

21121222001220 is a wasteful number, since it uses less digits than its factorization.

21121222001220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368807 (or 368802 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21121222001220 its reverse (2210022212112), we get a palindrome (23331244213332).

The spelling of 21121222001220 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty-two million, one thousand, two hundred twenty".