21100012 has 12 divisors (see below), whose sum is σ = 36967840.
Its totient is φ = 10537776.
The previous prime is 21100007. The next prime is 21100019. The reversal of 21100012 is 21000112.
It is a junction number, because it is equal to n+sod(n) for n = 21099968 and 21100004.
It is not an unprimeable number, because it can be changed into a prime (21100019) 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, 1618 + ... + 6694.
Almost surely, 221100012 is an apocalyptic number.
It is an amenable number.
21100012 is a deficient number, since it is larger than the sum of its proper divisors (15867828).
21100012 is a wasteful number, since it uses less digits than its factorization.
21100012 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 6120 (or 6118 counting only the distinct ones).
The product of its (nonzero) digits is 4, while the sum is 7.
The square root of 21100012 is about 4593.4749373432.
The cubic root of 21100012 is about 276.3297012102.
Adding to 21100012 its reverse (21000112), we get a palindrome (42100124).
The spelling of 21100012 in words is "twenty-one million, one hundred thousand, twelve".