21212112120 has 64 divisors (see below), whose sum is σ = 64122157440. Its totient is φ = 5613379200.

The previous prime is 21212112113. The next prime is 21212112121. The reversal of 21212112120 is 2121121212.

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 21212112120.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212112121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 658966 + ... + 690405.

It is an arithmetic number, because the mean of its divisors is an integer number (1001908710).

Almost surely, 2^21212112120 is an apocalyptic number.

21212112120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212112120 is an abundant number, since it is smaller than the sum of its proper divisors (42910045320).

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

21212112120 is a wasteful number, since it uses less digits than its factorization.

21212112120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1349516 (or 1349512 counting only the distinct ones).

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

Adding to 21212112120 its reverse (2121121212), we get a palindrome (23333233332).

The spelling of 21212112120 in words is "twenty-one billion, two hundred twelve million, one hundred twelve thousand, one hundred twenty".