21649328 has 20 divisors (see below), whose sum is σ = 42839520. Its totient is φ = 10593984.

The previous prime is 21649319. The next prime is 21649349. The reversal of 21649328 is 82394612.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13643 + ... + 15146.

It is an arithmetic number, because the mean of its divisors is an integer number (2141976).

Almost surely, 2^21649328 is an apocalyptic number.

It is an amenable number.

21649328 is a deficient number, since it is larger than the sum of its proper divisors (21190192).

21649328 is a wasteful number, since it uses less digits than its factorization.

21649328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28844 (or 28838 counting only the distinct ones).

The product of its digits is 20736, while the sum is 35.

The square root of 21649328 is about 4652.8838369338. The cubic root of 21649328 is about 278.7071691115.

The spelling of 21649328 in words is "twenty-one million, six hundred forty-nine thousand, three hundred twenty-eight".