21008064 has 224 divisors, whose sum is σ = 73152000. Its totient is φ = 5268480.

The previous prime is 21008041. The next prime is 21008081. The reversal of 21008064 is 46080012.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21008064.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 724402 + ... + 724430.

Almost surely, 2^21008064 is an apocalyptic number.

21008064 is a gapful number since it is divisible by the number (24) 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 21008064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36576000).

21008064 is an abundant number, since it is smaller than the sum of its proper divisors (52143936).

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

21008064 is a wasteful number, since it uses less digits than its factorization.

21008064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76 (or 52 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21008064 is about 4583.4554650394. The cubic root of 21008064 is about 275.9277273483.

Adding to 21008064 its reverse (46080012), we get a palindrome (67088076).

The spelling of 21008064 in words is "twenty-one million, eight thousand, sixty-four".