21100000012 has 48 divisors (see below), whose sum is σ = 45581273920. Its totient is φ = 8322435072.

The previous prime is 21100000001. The next prime is 21100000057. The reversal of 21100000012 is 21000000112.

It is a Harshad number since it is a multiple of its sum of digits (7).

It is a junction number, because it is equal to n+sod(n) for n = 21099999950 and 21100000004.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36664 + ... + 208672.

Almost surely, 2^21100000012 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21100000012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22790636960).

21100000012 is an abundant number, since it is smaller than the sum of its proper divisors (24481273908).

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

21100000012 is a wasteful number, since it uses less digits than its factorization.

21100000012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172370 (or 172368 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 21100000012 its reverse (21000000112), we get a palindrome (42100000124).

The spelling of 21100000012 in words is "twenty-one billion, one hundred million, twelve", and thus it is an aban number.