21549321 has 40 divisors (see below), whose sum is σ = 34499520. Its totient is φ = 13372128.

The previous prime is 21549301. The next prime is 21549389. The reversal of 21549321 is 12394512.

It is not a de Polignac number, because 21549321 - 2⁵ = 21549289 is a prime.

It is a super-2 number, since 2×21549321² = 928746471122082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21549301) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 79975 + ... + 80243.

It is an arithmetic number, because the mean of its divisors is an integer number (862488).

Almost surely, 2^21549321 is an apocalyptic number.

It is an amenable number.

21549321 is a deficient number, since it is larger than the sum of its proper divisors (12950199).

21549321 is a wasteful number, since it uses less digits than its factorization.

21549321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347 (or 338 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 21549321 is about 4642.1246213345. The cubic root of 21549321 is about 278.2773528955.

The spelling of 21549321 in words is "twenty-one million, five hundred forty-nine thousand, three hundred twenty-one".