21280524 has 12 divisors (see below), whose sum is σ = 49654584. Its totient is φ = 7093504.

The previous prime is 21280487. The next prime is 21280529. The reversal of 21280524 is 42508212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21280494 and 21280503.

It is not an unprimeable number, because it can be changed into a prime (21280529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 886677 + ... + 886700.

It is an arithmetic number, because the mean of its divisors is an integer number (4137882).

Almost surely, 2^21280524 is an apocalyptic number.

It is an amenable number.

21280524 is an abundant number, since it is smaller than the sum of its proper divisors (28374060).

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

21280524 is a wasteful number, since it uses less digits than its factorization.

21280524 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773384 (or 1773382 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21280524 is about 4613.0818332217. The cubic root of 21280524 is about 277.1154709792.

Adding to 21280524 its reverse (42508212), we get a palindrome (63788736).

The spelling of 21280524 in words is "twenty-one million, two hundred eighty thousand, five hundred twenty-four".