21420004 has 12 divisors (see below), whose sum is σ = 37609264. Its totient is φ = 10674504.

The previous prime is 21420001. The next prime is 21420013. The reversal of 21420004 is 40002412.

It is not an unprimeable number, because it can be changed into a prime (21420001) 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, 7494 + ... + 9949.

Almost surely, 2^21420004 is an apocalyptic number.

It is an amenable number.

21420004 is a deficient number, since it is larger than the sum of its proper divisors (16189260).

21420004 is a wasteful number, since it uses less digits than its factorization.

21420004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17754 (or 17752 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 13.

The square root of 21420004 is about 4628.1750182982. The cubic root of 21420004 is about 277.7195902772.

Adding to 21420004 its reverse (40002412), we get a palindrome (61422416).

The spelling of 21420004 in words is "twenty-one million, four hundred twenty thousand, four".