21111121212 has 12 divisors (see below), whose sum is σ = 49259282856. Its totient is φ = 7037040400.

The previous prime is 21111121211. The next prime is 21111121219. The reversal of 21111121212 is 21212111112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

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 = 21111121191 and 21111121200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111121211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 879630039 + ... + 879630062.

It is an arithmetic number, because the mean of its divisors is an integer number (4104940238).

Almost surely, 2^21111121212 is an apocalyptic number.

It is an amenable number.

21111121212 is an abundant number, since it is smaller than the sum of its proper divisors (28148161644).

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

21111121212 is a wasteful number, since it uses less digits than its factorization.

21111121212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1759260108 (or 1759260106 counting only the distinct ones).

The product of its digits is 16, while the sum is 15.

Adding to 21111121212 its reverse (21212111112), we get a palindrome (42323232324).

The spelling of 21111121212 in words is "twenty-one billion, one hundred eleven million, one hundred twenty-one thousand, two hundred twelve".