21130320 has 80 divisors (see below), whose sum is σ = 69370560. Its totient is φ = 5302272.

The previous prime is 21130301. The next prime is 21130321. The reversal of 21130320 is 2303112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21130296 and 21130305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21130321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1491 + ... + 6669.

It is an arithmetic number, because the mean of its divisors is an integer number (867132).

Almost surely, 2^21130320 is an apocalyptic number.

21130320 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 21130320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34685280).

21130320 is an abundant number, since it is smaller than the sum of its proper divisors (48240240).

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

21130320 is a wasteful number, since it uses less digits than its factorization.

21130320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5212 (or 5206 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21130320 is about 4596.7727809845. The cubic root of 21130320 is about 276.4619443236.

Adding to 21130320 its reverse (2303112), we get a palindrome (23433432).

The spelling of 21130320 in words is "twenty-one million, one hundred thirty thousand, three hundred twenty".