21281120 has 48 divisors (see below), whose sum is σ = 57462048. Its totient is φ = 7296000.

The previous prime is 21281111. The next prime is 21281137. The reversal of 21281120 is 2118212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8381 + ... + 10620.

It is an arithmetic number, because the mean of its divisors is an integer number (1197126).

Almost surely, 2^21281120 is an apocalyptic number.

21281120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21281120 is an abundant number, since it is smaller than the sum of its proper divisors (36180928).

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

21281120 is a wasteful number, since it uses less digits than its factorization.

21281120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19023 (or 19015 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 21281120 is about 4613.1464316668. The cubic root of 21281120 is about 277.1180579969.

Adding to 21281120 its reverse (2118212), we get a palindrome (23399332).

The spelling of 21281120 in words is "twenty-one million, two hundred eighty-one thousand, one hundred twenty".