21210212010221 has 16 divisors (see below), whose sum is σ = 24185830226544. Its totient is φ = 18426643820544.

The previous prime is 21210212010193. The next prime is 21210212010223. The reversal of 21210212010221 is 12201021201212.

It can be written as a sum of positive squares in 8 ways, for example, as 1346031554596 + 19864180455625 = 1160186^2 + 4456925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21210212010221 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21210212010221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210212010223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12041681 + ... + 13690233.

It is an arithmetic number, because the mean of its divisors is an integer number (1511614389159).

Almost surely, 2^{21210212010221} is an apocalyptic number.

It is an amenable number.

21210212010221 is a deficient number, since it is larger than the sum of its proper divisors (2975618216323).

21210212010221 is a wasteful number, since it uses less digits than its factorization.

21210212010221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1706800.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21210212010221 its reverse (12201021201212), we get a palindrome (33411233211433).

The spelling of 21210212010221 in words is "twenty-one trillion, two hundred ten billion, two hundred twelve million, ten thousand, two hundred twenty-one".