21129344 has 32 divisors (see below), whose sum is σ = 42301440. Its totient is φ = 10512640.

The previous prime is 21129343. The next prime is 21129359. The reversal of 21129344 is 44392112.

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21129343) by changing a digit.

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, 48809 + ... + 49239.

It is an arithmetic number, because the mean of its divisors is an integer number (1321920).

Almost surely, 2^21129344 is an apocalyptic number.

It is an amenable number.

21129344 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21129344 is an equidigital number, since it uses as much as digits as its factorization.

21129344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 828 (or 816 counting only the distinct ones).

The product of its digits is 1728, while the sum is 26.

The square root of 21129344 is about 4596.6666183225. Note that the first 4 decimals coincide. The cubic root of 21129344 is about 276.4576877070.

The spelling of 21129344 in words is "twenty-one million, one hundred twenty-nine thousand, three hundred forty-four".