21212121212 has 24 divisors (see below), whose sum is σ = 39949161840.
Its totient is φ = 9818530560.
The previous prime is 21212121209. The next prime is 21212121283.
21212121212 is nontrivially palindromic in base 10.
21212121212 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
It is a Harshad number since it is a multiple of its sum of digits (17).
It is a nude number because it is divisible by every one of its digits.
It is an alternating number because its digits alternate between even and odd.
21212121212 is an undulating number in base 10.
21212121212 is a modest number, since divided by 121212 gives 21212 as remainder.
It is a congruent number.
It is an unprimeable number.
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 7 ways as a sum of consecutive naturals, for example, 2552762 + ... + 2561057.
It is an arithmetic number, because the mean of its divisors is an integer number (1664548410).
Almost surely, 221212121212 is an apocalyptic number.
It is an amenable number.
21212121212 is a deficient number, since it is larger than the sum of its proper divisors (18737040628).
21212121212 is a wasteful number, since it uses less digits than its factorization.
21212121212 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 5113901 (or 5113899 counting only the distinct ones).
The product of its digits is 64, while the sum is 17.
The spelling of 21212121212 in words is "twenty-one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twelve".