21024016 has 40 divisors (see below), whose sum is σ = 44613464. Its totient is φ = 9538560.

The previous prime is 21023971. The next prime is 21024067. The reversal of 21024016 is 61042012.

It can be written as a sum of positive squares in 4 ways, for example, as 810000 + 20214016 = 900^2 + 4496^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

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, 11860 + ... + 13516.

Almost surely, 2^21024016 is an apocalyptic number.

21024016 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 21024016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22306732).

21024016 is an abundant number, since it is smaller than the sum of its proper divisors (23589448).

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

21024016 is a wasteful number, since it uses less digits than its factorization.

21024016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1739 (or 1733 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21024016 is about 4585.1953066363. The cubic root of 21024016 is about 275.9975495127.

Adding to 21024016 its reverse (61042012), we get a palindrome (82066028).

The spelling of 21024016 in words is "twenty-one million, twenty-four thousand, sixteen".