21004104 has 32 divisors (see below), whose sum is σ = 57284640. Its totient is φ = 6364800.

The previous prime is 21004099. The next prime is 21004117. The reversal of 21004104 is 40140012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21004104.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39517 + ... + 40044.

It is an arithmetic number, because the mean of its divisors is an integer number (1790145).

Almost surely, 2^21004104 is an apocalyptic number.

21004104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21004104 is an abundant number, since it is smaller than the sum of its proper divisors (36280536).

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

21004104 is a wasteful number, since it uses less digits than its factorization.

21004104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79581 (or 79577 counting only the distinct ones).

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

The square root of 21004104 is about 4583.0234561913. The cubic root of 21004104 is about 275.9103888878.

Adding to 21004104 its reverse (40140012), we get a palindrome (61144116).

The spelling of 21004104 in words is "twenty-one million, four thousand, one hundred four".