21321223220 has 96 divisors (see below), whose sum is σ = 49443803136. Its totient is φ = 7658496000.

The previous prime is 21321223163. The next prime is 21321223247. The reversal of 21321223220 is 2232212312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21321223192 and 21321223201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12820109 + ... + 12821771.

It is an arithmetic number, because the mean of its divisors is an integer number (515039616).

Almost surely, 2^21321223220 is an apocalyptic number.

21321223220 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 21321223220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24721901568).

21321223220 is an abundant number, since it is smaller than the sum of its proper divisors (28122579916).

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

21321223220 is a wasteful number, since it uses less digits than its factorization.

21321223220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2361 (or 2359 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21321223220 its reverse (2232212312), we get a palindrome (23553435532).

The spelling of 21321223220 in words is "twenty-one billion, three hundred twenty-one million, two hundred twenty-three thousand, two hundred twenty".