21329680 has 40 divisors (see below), whose sum is σ = 50443200. Its totient is φ = 8385408.

The previous prime is 21329663. The next prime is 21329683. The reversal of 21329680 is 8692312.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21329683) 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, 2461 + ... + 6979.

It is an arithmetic number, because the mean of its divisors is an integer number (1261080).

Almost surely, 2^21329680 is an apocalyptic number.

21329680 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 21329680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25221600).

21329680 is an abundant number, since it is smaller than the sum of its proper divisors (29113520).

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

21329680 is a wasteful number, since it uses less digits than its factorization.

21329680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4591 (or 4585 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21329680 is about 4618.4066516495. The cubic root of 21329680 is about 277.3286770873.

The spelling of 21329680 in words is "twenty-one million, three hundred twenty-nine thousand, six hundred eighty".