21912012 has 24 divisors (see below), whose sum is σ = 56809200. Its totient is φ = 7303968.

The previous prime is 21911987. The next prime is 21912013. The reversal of 21912012 is 21021912.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21912013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101337 + ... + 101552.

It is an arithmetic number, because the mean of its divisors is an integer number (2367050).

Almost surely, 2^21912012 is an apocalyptic number.

It is an amenable number.

21912012 is an abundant number, since it is smaller than the sum of its proper divisors (34897188).

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

21912012 is a wasteful number, since it uses less digits than its factorization.

21912012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202902 (or 202894 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21912012 is about 4681.0268104338. The cubic root of 21912012 is about 279.8298796537.

Adding to 21912012 its reverse (21021912), we get a palindrome (42933924).

The spelling of 21912012 in words is "twenty-one million, nine hundred twelve thousand, twelve".