21025520 has 20 divisors (see below), whose sum is σ = 48884520. Its totient is φ = 8410176.

The previous prime is 21025513. The next prime is 21025561. The reversal of 21025520 is 2552012.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 131330 + ... + 131489.

It is an arithmetic number, because the mean of its divisors is an integer number (2444226).

Almost surely, 2^21025520 is an apocalyptic number.

21025520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21025520 is an abundant number, since it is smaller than the sum of its proper divisors (27859000).

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

21025520 is a wasteful number, since it uses less digits than its factorization.

21025520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262832 (or 262826 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 17.

The square root of 21025520 is about 4585.3593098033. The cubic root of 21025520 is about 276.0041307230.

Adding to 21025520 its reverse (2552012), we get a palindrome (23577532).

The spelling of 21025520 in words is "twenty-one million, twenty-five thousand, five hundred twenty".