21450520 has 128 divisors (see below), whose sum is σ = 60963840. Its totient is φ = 6612480.

The previous prime is 21450511. The next prime is 21450521. The reversal of 21450520 is 2505412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21450521) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 258399 + ... + 258481.

It is an arithmetic number, because the mean of its divisors is an integer number (476280).

Almost surely, 2^21450520 is an apocalyptic number.

21450520 is a gapful number since it is divisible by the number (20) 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 21450520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30481920).

21450520 is an abundant number, since it is smaller than the sum of its proper divisors (39513320).

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

21450520 is a wasteful number, since it uses less digits than its factorization.

21450520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185 (or 181 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21450520 is about 4631.4706087808. The cubic root of 21450520 is about 277.8514120642.

Adding to 21450520 its reverse (2505412), we get a palindrome (23955932).

The spelling of 21450520 in words is "twenty-one million, four hundred fifty thousand, five hundred twenty".