21222212121220 has 72 divisors (see below), whose sum is σ = 48989189679192. Its totient is φ = 7716740866560.

The previous prime is 21222212121197. The next prime is 21222212121223. The reversal of 21222212121220 is 2212121222212.

It can be written as a sum of positive squares in 4 ways, for example, as 1886211079236 + 19336001041984 = 1373394^2 + 4397272^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21222212121191 and 21222212121200.

It is not an unprimeable number, because it can be changed into a prime (21222212121223) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 45245742 + ... + 45712378.

It is an arithmetic number, because the mean of its divisors is an integer number (680405412211).

Almost surely, 2^{21222212121220} is an apocalyptic number.

21222212121220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21222212121220 is an abundant number, since it is smaller than the sum of its proper divisors (27766977557972).

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

21222212121220 is a wasteful number, since it uses less digits than its factorization.

21222212121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485461 (or 485448 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

Adding to 21222212121220 its reverse (2212121222212), we get a palindrome (23434333343432).

The spelling of 21222212121220 in words is "twenty-one trillion, two hundred twenty-two billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twenty".