21428484 has 72 divisors (see below), whose sum is σ = 63469728. Its totient is φ = 5564160.

The previous prime is 21428461. The next prime is 21428489. The reversal of 21428484 is 48482412.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21428489) 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 23 ways as a sum of consecutive naturals, for example, 4812 + ... + 8124.

It is an arithmetic number, because the mean of its divisors is an integer number (881524).

Almost surely, 2^21428484 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 21428484, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31734864).

21428484 is an abundant number, since it is smaller than the sum of its proper divisors (42041244).

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

21428484 is a wasteful number, since it uses less digits than its factorization.

21428484 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3345 (or 3336 counting only the distinct ones).

The product of its digits is 16384, while the sum is 33.

The square root of 21428484 is about 4629.0910554881. The cubic root of 21428484 is about 277.7562343944.

It can be divided in two parts, 21428 and 484, that added together give a palindrome (21912).

The spelling of 21428484 in words is "twenty-one million, four hundred twenty-eight thousand, four hundred eighty-four".