21361320 has 160 divisors (see below), whose sum is σ = 75794400. Its totient is φ = 5380992.

The previous prime is 21361303. The next prime is 21361391. The reversal of 21361320 is 2316312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21361293 and 21361302.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 61387 + ... + 61733.

It is an arithmetic number, because the mean of its divisors is an integer number (473715).

Almost surely, 2^21361320 is an apocalyptic number.

21361320 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 21361320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37897200).

21361320 is an abundant number, since it is smaller than the sum of its proper divisors (54433080).

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

21361320 is a wasteful number, since it uses less digits than its factorization.

21361320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389 (or 376 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21361320 is about 4621.8308060767. The cubic root of 21361320 is about 277.4657371869.

Adding to 21361320 its reverse (2316312), we get a palindrome (23677632).

The spelling of 21361320 in words is "twenty-one million, three hundred sixty-one thousand, three hundred twenty".