20421320 has 32 divisors (see below), whose sum is σ = 46509120. Its totient is φ = 8068800.

The previous prime is 20421287. The next prime is 20421329. The reversal of 20421320 is 2312402.

It is a junction number, because it is equal to n+sod(n) for n = 20421295 and 20421304.

It is not an unprimeable number, because it can be changed into a prime (20421329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 245 + ... + 6395.

It is an arithmetic number, because the mean of its divisors is an integer number (1453410).

Almost surely, 2^20421320 is an apocalyptic number.

20421320 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 20421320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23254560).

20421320 is an abundant number, since it is smaller than the sum of its proper divisors (26087800).

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

20421320 is a wasteful number, since it uses less digits than its factorization.

20421320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6245 (or 6241 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 20421320 is about 4518.9954635959. The cubic root of 20421320 is about 273.3345958035.

Adding to 20421320 its reverse (2312402), we get a palindrome (22733722).

The spelling of 20421320 in words is "twenty million, four hundred twenty-one thousand, three hundred twenty".