21111111221212 has 12 divisors (see below), whose sum is σ = 39117647262960. Its totient is φ = 9934640574656.

The previous prime is 21111111221203. The next prime is 21111111221371. The reversal of 21111111221212 is 21212211111112.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21111111221212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 155228758912 + ... + 155228759047.

It is an arithmetic number, because the mean of its divisors is an integer number (3259803938580).

Almost surely, 2^{21111111221212} is an apocalyptic number.

It is an amenable number.

21111111221212 is a deficient number, since it is larger than the sum of its proper divisors (18006536041748).

21111111221212 is a wasteful number, since it uses less digits than its factorization.

21111111221212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310457517980 (or 310457517978 counting only the distinct ones).

The product of its digits is 32, while the sum is 19.

Adding to 21111111221212 its reverse (21212211111112), we get a palindrome (42323322332324).

The spelling of 21111111221212 in words is "twenty-one trillion, one hundred eleven billion, one hundred eleven million, two hundred twenty-one thousand, two hundred twelve".