21055321 has 8 divisors (see below), whose sum is σ = 24105600. Its totient is φ = 18015648.

The previous prime is 21055319. The next prime is 21055343. The reversal of 21055321 is 12355012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21055321 - 2¹ = 21055319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21055301) 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 7 ways as a sum of consecutive naturals, for example, 2205 + ... + 6853.

It is an arithmetic number, because the mean of its divisors is an integer number (3013200).

Almost surely, 2^21055321 is an apocalyptic number.

It is an amenable number.

21055321 is a deficient number, since it is larger than the sum of its proper divisors (3050279).

21055321 is an equidigital number, since it uses as much as digits as its factorization.

21055321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5303.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21055321 is about 4588.6077409166. The cubic root of 21055321 is about 276.1344694114.

The spelling of 21055321 in words is "twenty-one million, fifty-five thousand, three hundred twenty-one".