21228064 has 48 divisors (see below), whose sum is σ = 49109760. Its totient is φ = 8904960.

The previous prime is 21228059. The next prime is 21228089. The reversal of 21228064 is 46082212.

It is a happy number.

It is a super-3 number, since 3×21228064³ (a number of 23 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2257 + ... + 6895.

It is an arithmetic number, because the mean of its divisors is an integer number (1023120).

Almost surely, 2^21228064 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21228064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24554880).

21228064 is an abundant number, since it is smaller than the sum of its proper divisors (27881696).

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

21228064 is a wasteful number, since it uses less digits than its factorization.

21228064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4673 (or 4665 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 25.

The square root of 21228064 is about 4607.3923210423. The cubic root of 21228064 is about 276.8875718329.

The spelling of 21228064 in words is "twenty-one million, two hundred twenty-eight thousand, sixty-four".