21100104 has 48 divisors (see below), whose sum is σ = 57442320. Its totient is φ = 6996960.

The previous prime is 21100103. The next prime is 21100129. The reversal of 21100104 is 40100112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21100103) 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 11 ways as a sum of consecutive naturals, for example, 15699 + ... + 16989.

It is an arithmetic number, because the mean of its divisors is an integer number (1196715).

Almost surely, 2^21100104 is an apocalyptic number.

21100104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21100104 is an abundant number, since it is smaller than the sum of its proper divisors (36342216).

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

21100104 is a wasteful number, since it uses less digits than its factorization.

21100104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1530 (or 1523 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21100104 is about 4593.4849515373. The cubic root of 21100104 is about 276.3301028260.

Adding to 21100104 its reverse (40100112), we get a palindrome (61200216).

The spelling of 21100104 in words is "twenty-one million, one hundred thousand, one hundred four".