21204012 has 12 divisors (see below), whose sum is σ = 49476056. Its totient is φ = 7068000.

The previous prime is 21203977. The next prime is 21204013. The reversal of 21204012 is 21040212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21204012² = 899220249792288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12), and also a Moran number because the ratio is a prime number: 1767001 = 21204012 / (2 + 1 + 2 + 0 + 4 + 0 + 1 + 2).

It is not an unprimeable number, because it can be changed into a prime (21204013) 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, 883489 + ... + 883512.

Almost surely, 2^21204012 is an apocalyptic number.

It is an amenable number.

21204012 is an abundant number, since it is smaller than the sum of its proper divisors (28272044).

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

21204012 is a wasteful number, since it uses less digits than its factorization.

21204012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1767008 (or 1767006 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21204012 is about 4604.7814280376. The cubic root of 21204012 is about 276.7829584828.

Adding to 21204012 its reverse (21040212), we get a palindrome (42244224).

The spelling of 21204012 in words is "twenty-one million, two hundred four thousand, twelve".