20721324 has 48 divisors (see below), whose sum is σ = 54817280. Its totient is φ = 6039360.

The previous prime is 20721319. The next prime is 20721329. The reversal of 20721324 is 42312702.

It is an interprime number because it is at equal distance from previous prime (20721319) and next prime (20721329).

It is a self number, because there is not a number n which added to its sum of digits gives 20721324.

It is not an unprimeable number, because it can be changed into a prime (20721329) 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 15 ways as a sum of consecutive naturals, for example, 532 + ... + 6459.

Almost surely, 2^20721324 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 20721324, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27408640).

20721324 is an abundant number, since it is smaller than the sum of its proper divisors (34095956).

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

20721324 is a wasteful number, since it uses less digits than its factorization.

20721324 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7030 (or 7028 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 20721324 is about 4552.0681014238. The cubic root of 20721324 is about 274.6665887716. Note that the first 3 decimals are identical.

The spelling of 20721324 in words is "twenty million, seven hundred twenty-one thousand, three hundred twenty-four".