21004012 has 24 divisors (see below), whose sum is σ = 38059280. Its totient is φ = 10134720.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21004012 is 21040012.

It is a super-2 number, since 2×21004012² = 882337040192288, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21004012.

It is an unprimeable number.

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, 20062 + ... + 21082.

Almost surely, 2^21004012 is an apocalyptic number.

It is an amenable number.

21004012 is a deficient number, since it is larger than the sum of its proper divisors (17055268).

21004012 is a wasteful number, since it uses less digits than its factorization.

21004012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1201 (or 1199 counting only the distinct ones).

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

The square root of 21004012 is about 4583.0134191381. The cubic root of 21004012 is about 275.9099860492.

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

The spelling of 21004012 in words is "twenty-one million, four thousand, twelve".