21121210110 has 512 divisors, whose sum is σ = 71530905600. Its totient is φ = 3849431040.

The previous prime is 21121210087. The next prime is 21121210151. The reversal of 21121210110 is 1101212112.

It is a super-2 number, since 2×21121210110² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 68798577 + ... + 68798883.

It is an arithmetic number, because the mean of its divisors is an integer number (139708800).

Almost surely, 2^21121210110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21121210110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35765452800).

21121210110 is an abundant number, since it is smaller than the sum of its proper divisors (50409695490).

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

21121210110 is a wasteful number, since it uses less digits than its factorization.

21121210110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 456.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21121210110 its reverse (1101212112), we get a palindrome (22222422222).

The spelling of 21121210110 in words is "twenty-one billion, one hundred twenty-one million, two hundred ten thousand, one hundred ten".