21128284 has 12 divisors (see below), whose sum is σ = 37876608. Its totient is φ = 10306400.

The previous prime is 21128281. The next prime is 21128293. The reversal of 21128284 is 48282112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64252 + ... + 64579.

It is an arithmetic number, because the mean of its divisors is an integer number (3156384).

Almost surely, 2^21128284 is an apocalyptic number.

It is an amenable number.

21128284 is a deficient number, since it is larger than the sum of its proper divisors (16748324).

21128284 is a wasteful number, since it uses less digits than its factorization.

21128284 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128876 (or 128874 counting only the distinct ones).

The product of its digits is 2048, while the sum is 28.

The square root of 21128284 is about 4596.5513159324. The cubic root of 21128284 is about 276.4530645938.

It can be divided in two parts, 21128 and 284, that added together give a palindrome (21412).

The spelling of 21128284 in words is "twenty-one million, one hundred twenty-eight thousand, two hundred eighty-four".