21001221102210 has 128 divisors (see below), whose sum is σ = 52532542960128. Its totient is φ = 5368301568000.

The previous prime is 21001221102193. The next prime is 21001221102233. The reversal of 21001221102210 is 1220112210012.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21001221102210.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 108740130 + ... + 108933090.

It is an arithmetic number, because the mean of its divisors is an integer number (410410491876).

Almost surely, 2^{21001221102210} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21001221102210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26266271480064).

21001221102210 is an abundant number, since it is smaller than the sum of its proper divisors (31531321857918).

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

21001221102210 is a wasteful number, since it uses less digits than its factorization.

21001221102210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194460.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21001221102210 its reverse (1220112210012), we get a palindrome (22221333312222).

The spelling of 21001221102210 in words is "twenty-one trillion, one billion, two hundred twenty-one million, one hundred two thousand, two hundred ten".