21226520 has 96 divisors (see below), whose sum is σ = 57244320. Its totient is φ = 6935040.

The previous prime is 21226519. The next prime is 21226531. The reversal of 21226520 is 2562212.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21226492 and 21226501.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 493619 + ... + 493661.

It is an arithmetic number, because the mean of its divisors is an integer number (596295).

Almost surely, 2^21226520 is an apocalyptic number.

21226520 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 21226520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28622160).

21226520 is an abundant number, since it is smaller than the sum of its proper divisors (36017800).

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

21226520 is a wasteful number, since it uses less digits than its factorization.

21226520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 98 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21226520 is about 4607.2247611767. The cubic root of 21226520 is about 276.8808586320.

Adding to 21226520 its reverse (2562212), we get a palindrome (23788732).

The spelling of 21226520 in words is "twenty-one million, two hundred twenty-six thousand, five hundred twenty".