21222121110 has 64 divisors (see below), whose sum is σ = 52368712704. Its totient is φ = 5500742400.

The previous prime is 21222121097. The next prime is 21222121121. The reversal of 21222121110 is 1112122212.

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

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21222121110.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 301497 + ... + 365163.

It is an arithmetic number, because the mean of its divisors is an integer number (818261136).

Almost surely, 2^21222121110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21222121110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26184356352).

21222121110 is an abundant number, since it is smaller than the sum of its proper divisors (31146591594).

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

21222121110 is a wasteful number, since it uses less digits than its factorization.

21222121110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63989.

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

Adding to 21222121110 its reverse (1112122212), we get a palindrome (22334243322).

The spelling of 21222121110 in words is "twenty-one billion, two hundred twenty-two million, one hundred twenty-one thousand, one hundred ten".