21002201220 has 576 divisors, whose sum is σ = 81648193536. Its totient is φ = 3914127360.

The previous prime is 21002201179. The next prime is 21002201249. The reversal of 21002201220 is 2210220012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21002201196 and 21002201205.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 28888497 + ... + 28889223.

It is an arithmetic number, because the mean of its divisors is an integer number (141750336).

Almost surely, 2^21002201220 is an apocalyptic number.

21002201220 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 21002201220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40824096768).

21002201220 is an abundant number, since it is smaller than the sum of its proper divisors (60645992316).

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

21002201220 is a wasteful number, since it uses less digits than its factorization.

21002201220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 820 (or 805 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21002201220 its reverse (2210220012), we get a palindrome (23212421232).

It can be divided in two parts, 21002 and 201220, that added together give a palindrome (222222).

The spelling of 21002201220 in words is "twenty-one billion, two million, two hundred one thousand, two hundred twenty".