21104100 has 108 divisors (see below), whose sum is σ = 67026960. Its totient is φ = 5553600.

The previous prime is 21104071. The next prime is 21104131. The reversal of 21104100 is 140112.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 117811 + ... + 117989.

It is an arithmetic number, because the mean of its divisors is an integer number (620620).

Almost surely, 2^21104100 is an apocalyptic number.

21104100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21104100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33513480).

21104100 is an abundant number, since it is smaller than the sum of its proper divisors (45922860).

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

21104100 is a wasteful number, since it uses less digits than its factorization.

21104100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330 (or 320 counting only the distinct ones).

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

The square root of 21104100 is about 4593.9198948175. The cubic root of 21104100 is about 276.3475457952.

Adding to 21104100 its reverse (140112), we get a palindrome (21244212).

The spelling of 21104100 in words is "twenty-one million, one hundred four thousand, one hundred".