21040012 has 18 divisors (see below), whose sum is σ = 42831852. Its totient is φ = 9017064.

The previous prime is 21040007. The next prime is 21040039. The reversal of 21040012 is 21004012.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 53478 + ... + 53869.

Almost surely, 2^21040012 is an apocalyptic number.

It is an amenable number.

21040012 is an abundant number, since it is smaller than the sum of its proper divisors (21791840).

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

21040012 is a wasteful number, since it uses less digits than its factorization.

21040012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107365 (or 107356 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21040012 is about 4586.9392845339. The cubic root of 21040012 is about 276.0675288100.

Adding to 21040012 its reverse (21004012), we get a palindrome (42044024).

The spelling of 21040012 in words is "twenty-one million, forty thousand, twelve".