21121104 has 20 divisors (see below), whose sum is σ = 54562976. Its totient is φ = 7040352.

The previous prime is 21121099. The next prime is 21121129. The reversal of 21121104 is 40112112.

It is a happy number.

It is a super-2 number, since 2×21121104² = 892202068357632, which contains 22 as substring.

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 21121104.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219964 + ... + 220059.

Almost surely, 2^21121104 is an apocalyptic number.

21121104 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21121104 is an abundant number, since it is smaller than the sum of its proper divisors (33441872).

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

21121104 is a wasteful number, since it uses less digits than its factorization.

21121104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 440034 (or 440028 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21121104 is about 4595.7702292434. The cubic root of 21121104 is about 276.4217454721.

Adding to 21121104 its reverse (40112112), we get a palindrome (61233216).

The spelling of 21121104 in words is "twenty-one million, one hundred twenty-one thousand, one hundred four".