20999424 has 72 divisors (see below), whose sum is σ = 57477280. Its totient is φ = 6801408.

The previous prime is 20999423. The next prime is 20999443. The reversal of 20999424 is 42499902.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20999423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28047 + ... + 28785.

Almost surely, 2^20999424 is an apocalyptic number.

20999424 is a gapful number since it is divisible by the number (24) 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 20999424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28738640).

20999424 is an abundant number, since it is smaller than the sum of its proper divisors (36477856).

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

20999424 is an equidigital number, since it uses as much as digits as its factorization.

20999424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 795 (or 781 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 20999424 is about 4582.5128477725. The cubic root of 20999424 is about 275.8898951701.

The spelling of 20999424 in words is "twenty million, nine hundred ninety-nine thousand, four hundred twenty-four".