20421324 has 144 divisors (see below), whose sum is σ = 66044160. Its totient is φ = 5166720.

The previous prime is 20421287. The next prime is 20421329. The reversal of 20421324 is 42312402.

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

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 20421297 and 20421306.

It is a congruent number.

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

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 146847 + ... + 146985.

It is an arithmetic number, because the mean of its divisors is an integer number (458640).

Almost surely, 2^20421324 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20421324, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33022080).

20421324 is an abundant number, since it is smaller than the sum of its proper divisors (45622836).

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

20421324 is a wasteful number, since it uses less digits than its factorization.

20421324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220 (or 215 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 20421324 is about 4518.9959061721. The cubic root of 20421324 is about 273.3346136499.

Adding to 20421324 its reverse (42312402), we get a palindrome (62733726).

It can be divided in two parts, 204 and 21324, that added together give a triangular number (21528 = T₂₀₇).

The spelling of 20421324 in words is "twenty million, four hundred twenty-one thousand, three hundred twenty-four".