21428748 has 72 divisors (see below), whose sum is σ = 60265296. Its totient is φ = 6364800.

The previous prime is 21428747. The next prime is 21428791. The reversal of 21428748 is 84782412.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21428747) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20478 + ... + 21498.

It is an arithmetic number, because the mean of its divisors is an integer number (837018).

Almost surely, 2^21428748 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 21428748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30132648).

21428748 is an abundant number, since it is smaller than the sum of its proper divisors (38836548).

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

21428748 is a wasteful number, since it uses less digits than its factorization.

21428748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1095 (or 1090 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 21428748 is about 4629.1195707175. The cubic root of 21428748 is about 277.7573750466.

The spelling of 21428748 in words is "twenty-one million, four hundred twenty-eight thousand, seven hundred forty-eight".