21000104 has 32 divisors (see below), whose sum is σ = 41783040. Its totient is φ = 9873600.

The previous prime is 21000103. The next prime is 21000121. The reversal of 21000104 is 40100012.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a junction number, because it is equal to n+sod(n) for n = 21000091 and 21000100.

It is not an unprimeable number, because it can be changed into a prime (21000103) by changing a digit.

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, 10289 + ... + 12159.

It is an arithmetic number, because the mean of its divisors is an integer number (1305720).

Almost surely, 2^21000104 is an apocalyptic number.

It is an amenable number.

21000104 is a deficient number, since it is larger than the sum of its proper divisors (20782936).

21000104 is a wasteful number, since it uses less digits than its factorization.

21000104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1961 (or 1957 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

The square root of 21000104 is about 4582.5870422721. The cubic root of 21000104 is about 275.8928730788.

Adding to 21000104 its reverse (40100012), we get a palindrome (61100116).

The spelling of 21000104 in words is "twenty-one million, one hundred four", and thus it is an aban number.