21738920 has 64 divisors (see below), whose sum is σ = 59201280. Its totient is φ = 7013376.

The previous prime is 21738919. The next prime is 21738929. The reversal of 21738920 is 2983712.

It is not an unprimeable number, because it can be changed into a prime (21738929) 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, 2477 + ... + 7043.

It is an arithmetic number, because the mean of its divisors is an integer number (925020).

Almost surely, 2^21738920 is an apocalyptic number.

21738920 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 21738920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29600640).

21738920 is an abundant number, since it is smaller than the sum of its proper divisors (37462360).

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

21738920 is a wasteful number, since it uses less digits than its factorization.

21738920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4602 (or 4598 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 21738920 is about 4662.5014745306. The cubic root of 21738920 is about 279.0911004601.

The spelling of 21738920 in words is "twenty-one million, seven hundred thirty-eight thousand, nine hundred twenty".