210221512660 has 72 divisors (see below), whose sum is σ = 466248673800. Its totient is φ = 79607225088.

The previous prime is 210221512621. The next prime is 210221512703. The reversal of 210221512660 is 66215122012.

It can be written as a sum of positive squares in 4 ways, for example, as 34797917764 + 175423594896 = 186542^2 + 418836^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11174382 + ... + 11193178.

It is an arithmetic number, because the mean of its divisors is an integer number (6475676025).

Almost surely, 2^210221512660 is an apocalyptic number.

210221512660 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 210221512660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (233124336900).

210221512660 is an abundant number, since it is smaller than the sum of its proper divisors (256027161140).

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

210221512660 is a wasteful number, since it uses less digits than its factorization.

210221512660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20393 (or 20372 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

Adding to 210221512660 its reverse (66215122012), we get a palindrome (276436634672).

The spelling of 210221512660 in words is "two hundred ten billion, two hundred twenty-one million, five hundred twelve thousand, six hundred sixty".