21438774 has 72 divisors (see below), whose sum is σ = 54774720. Its totient is φ = 6041952.

The previous prime is 21438757. The next prime is 21438779. The reversal of 21438774 is 47783412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21438779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 96027 + ... + 96249.

It is an arithmetic number, because the mean of its divisors is an integer number (760760).

Almost surely, 2^21438774 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21438774, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27387360).

21438774 is an abundant number, since it is smaller than the sum of its proper divisors (33335946).

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

21438774 is a wasteful number, since it uses less digits than its factorization.

21438774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 354 (or 344 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The square root of 21438774 is about 4630.2023713872. The cubic root of 21438774 is about 277.8006869757.

The spelling of 21438774 in words is "twenty-one million, four hundred thirty-eight thousand, seven hundred seventy-four".