21013355220 has 288 divisors, whose sum is σ = 72534196224. Its totient is φ = 4497292800.

The previous prime is 21013355191. The next prime is 21013355249. The reversal of 21013355220 is 2255331012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21013355191) and next prime (21013355249).

It is a super-2 number, since 2×21013355220² (a number of 21 digits) contains 22 as substring.

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 95 ways as a sum of consecutive naturals, for example, 2561325 + ... + 2569515.

It is an arithmetic number, because the mean of its divisors is an integer number (251854848).

Almost surely, 2^21013355220 is an apocalyptic number.

21013355220 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 21013355220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36267098112).

21013355220 is an abundant number, since it is smaller than the sum of its proper divisors (51520841004).

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

21013355220 is a wasteful number, since it uses less digits than its factorization.

21013355220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8263 (or 8248 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 24.

Adding to 21013355220 its reverse (2255331012), we get a palindrome (23268686232).

The spelling of 21013355220 in words is "twenty-one billion, thirteen million, three hundred fifty-five thousand, two hundred twenty".