21328398 has 96 divisors (see below), whose sum is σ = 58968000. Its totient is φ = 5419008.

The previous prime is 21328381. The next prime is 21328399. The reversal of 21328398 is 89382312.

It is a happy number.

It is a super-2 number, since 2×21328398² = 909801122492808, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21328399) 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 47 ways as a sum of consecutive naturals, for example, 47278 + ... + 47726.

It is an arithmetic number, because the mean of its divisors is an integer number (614250).

Almost surely, 2^21328398 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21328398, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29484000).

21328398 is an abundant number, since it is smaller than the sum of its proper divisors (37639602).

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

21328398 is a wasteful number, since it uses less digits than its factorization.

21328398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506 (or 503 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 21328398 is about 4618.2678571083. The cubic root of 21328398 is about 277.3231207845.

The spelling of 21328398 in words is "twenty-one million, three hundred twenty-eight thousand, three hundred ninety-eight".