21121320220 has 192 divisors, whose sum is σ = 60105830400. Its totient is φ = 6020490240.

The previous prime is 21121320203. The next prime is 21121320257. The reversal of 21121320220 is 2202312112.

It is a happy number.

It is a super-2 number, since 2×21121320220² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121320194 and 21121320203.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2177341 + ... + 2187019.

It is an arithmetic number, because the mean of its divisors is an integer number (313051200).

Almost surely, 2^21121320220 is an apocalyptic number.

21121320220 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 21121320220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30052915200).

21121320220 is an abundant number, since it is smaller than the sum of its proper divisors (38984510180).

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

21121320220 is a wasteful number, since it uses less digits than its factorization.

21121320220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9828 (or 9826 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21121320220 its reverse (2202312112), we get a palindrome (23323632332).

The spelling of 21121320220 in words is "twenty-one billion, one hundred twenty-one million, three hundred twenty thousand, two hundred twenty".