21504004 has 24 divisors (see below), whose sum is σ = 38828160. Its totient is φ = 10415136.

The previous prime is 21503981. The next prime is 21504017. The reversal of 21504004 is 40040512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19582 + ... + 20650.

It is an arithmetic number, because the mean of its divisors is an integer number (1617840).

Almost surely, 2^21504004 is an apocalyptic number.

It is an amenable number.

21504004 is a deficient number, since it is larger than the sum of its proper divisors (17324156).

21504004 is a wasteful number, since it uses less digits than its factorization.

21504004 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1227 (or 1225 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21504004 is about 4637.2409900716. The cubic root of 21504004 is about 278.0821488331.

Adding to 21504004 its reverse (40040512), we get a palindrome (61544516).

The spelling of 21504004 in words is "twenty-one million, five hundred four thousand, four".