21672324 has 72 divisors (see below), whose sum is σ = 56871360. Its totient is φ = 6955200.

The previous prime is 21672323. The next prime is 21672337. The reversal of 21672324 is 42327612.

It is not an unprimeable number, because it can be changed into a prime (21672323) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 155847 + ... + 155985.

It is an arithmetic number, because the mean of its divisors is an integer number (789880).

Almost surely, 2^21672324 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 21672324, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28435680).

21672324 is an abundant number, since it is smaller than the sum of its proper divisors (35199036).

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

21672324 is a wasteful number, since it uses less digits than its factorization.

21672324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281 (or 276 counting only the distinct ones).

The product of its digits is 4032, while the sum is 27.

The square root of 21672324 is about 4655.3543366751. The cubic root of 21672324 is about 278.8058154701.

Adding to 21672324 its reverse (42327612), we get a palindrome (63999936).

The spelling of 21672324 in words is "twenty-one million, six hundred seventy-two thousand, three hundred twenty-four".