21428316 has 144 divisors (see below), whose sum is σ = 69142528. Its totient is φ = 5443200.

The previous prime is 21428243. The next prime is 21428317. The reversal of 21428316 is 61382412.

It is a self number, because there is not a number n which added to its sum of digits gives 21428316.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21428317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 101451 + ... + 101661.

Almost surely, 2^21428316 is an apocalyptic number.

21428316 is a gapful number since it is divisible by the number (26) 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 21428316, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34571264).

21428316 is an abundant number, since it is smaller than the sum of its proper divisors (47714212).

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

21428316 is a wasteful number, since it uses less digits than its factorization.

21428316 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272 (or 267 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21428316 is about 4629.0729093416. The cubic root of 21428316 is about 277.7555085199.

The spelling of 21428316 in words is "twenty-one million, four hundred twenty-eight thousand, three hundred sixteen".