21126320 has 40 divisors (see below), whose sum is σ = 49423920. Its totient is φ = 8398080.

The previous prime is 21126317. The next prime is 21126337. The reversal of 21126320 is 2362112.

It is a tau number, because it is divible by the number of its divisors (40).

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, 13751 + ... + 15209.

It is an arithmetic number, because the mean of its divisors is an integer number (1235598).

Almost surely, 2^21126320 is an apocalyptic number.

21126320 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 21126320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24711960).

21126320 is an abundant number, since it is smaller than the sum of its proper divisors (28297600).

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

21126320 is a wasteful number, since it uses less digits than its factorization.

21126320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1653 (or 1647 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21126320 is about 4596.3376725389. The cubic root of 21126320 is about 276.4444983413. Note that the first 4 decimals are identical.

Adding to 21126320 its reverse (2362112), we get a palindrome (23488432).

The spelling of 21126320 in words is "twenty-one million, one hundred twenty-six thousand, three hundred twenty".