21121212216 has 64 divisors (see below), whose sum is σ = 60209805600. Its totient is φ = 6116548608.

The previous prime is 21121212209. The next prime is 21121212253. The reversal of 21121212216 is 61221212112.

It is a super-2 number, since 2×21121212216² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21121212192 and 21121212201.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1985761 + ... + 1996368.

Almost surely, 2^21121212216 is an apocalyptic number.

21121212216 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21121212216 is an abundant number, since it is smaller than the sum of its proper divisors (39088593384).

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

21121212216 is a wasteful number, since it uses less digits than its factorization.

21121212216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3982168 (or 3982164 counting only the distinct ones).

The product of its digits is 192, while the sum is 21.

Adding to 21121212216 its reverse (61221212112), we get a palindrome (82342424328).

The spelling of 21121212216 in words is "twenty-one billion, one hundred twenty-one million, two hundred twelve thousand, two hundred sixteen".