21329280 has 288 divisors, whose sum is σ = 87993360. Its totient is φ = 4663296.

The previous prime is 21329263. The next prime is 21329299. The reversal of 21329280 is 8292312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 927349 + ... + 927371.

Almost surely, 2^21329280 is an apocalyptic number.

21329280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21329280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43996680).

21329280 is an abundant number, since it is smaller than the sum of its proper divisors (66664080).

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

21329280 is a wasteful number, since it uses less digits than its factorization.

21329280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78 (or 40 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21329280 is about 4618.3633464681. The cubic root of 21329280 is about 277.3269434754.

It can be divided in two parts, 21329 and 280, that added together give a square (21609 = 147²).

The spelling of 21329280 in words is "twenty-one million, three hundred twenty-nine thousand, two hundred eighty".