21102121212 has 12 divisors (see below), whose sum is σ = 49238282856. Its totient is φ = 7034040400.

The previous prime is 21102121153. The next prime is 21102121217. The reversal of 21102121212 is 21212120112.

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

It is a junction number, because it is equal to n+sod(n) for n = 21102121191 and 21102121200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102121217) 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, 879255039 + ... + 879255062.

It is an arithmetic number, because the mean of its divisors is an integer number (4103190238).

Almost surely, 2^21102121212 is an apocalyptic number.

It is an amenable number.

21102121212 is an abundant number, since it is smaller than the sum of its proper divisors (28136161644).

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

21102121212 is a wasteful number, since it uses less digits than its factorization.

21102121212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1758510108 (or 1758510106 counting only the distinct ones).

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

Adding to 21102121212 its reverse (21212120112), we get a palindrome (42314241324).

The spelling of 21102121212 in words is "twenty-one billion, one hundred two million, one hundred twenty-one thousand, two hundred twelve".