21284064 has 72 divisors (see below), whose sum is σ = 60972912. Its totient is φ = 7042560.

The previous prime is 21284041. The next prime is 21284093. The reversal of 21284064 is 46048212.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×21284064² = 906022760712192, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 75604 + ... + 75884.

It is an arithmetic number, because the mean of its divisors is an integer number (846846).

Almost surely, 2^21284064 is an apocalyptic number.

21284064 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 21284064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30486456).

21284064 is an abundant number, since it is smaller than the sum of its proper divisors (39688848).

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

21284064 is a wasteful number, since it uses less digits than its factorization.

21284064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 560 (or 549 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 21284064 is about 4613.4655087038. The cubic root of 21284064 is about 277.1308361142.

The spelling of 21284064 in words is "twenty-one million, two hundred eighty-four thousand, sixty-four".