21115744 has 48 divisors (see below), whose sum is σ = 45172512. Its totient is φ = 9658368.

The previous prime is 21115739. The next prime is 21115747. The reversal of 21115744 is 44751112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115747) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80157 + ... + 80419.

It is an arithmetic number, because the mean of its divisors is an integer number (941094).

Almost surely, 2^21115744 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 21115744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22586256).

21115744 is an abundant number, since it is smaller than the sum of its proper divisors (24056768).

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

21115744 is a wasteful number, since it uses less digits than its factorization.

21115744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 479 (or 471 counting only the distinct ones).

The product of its digits is 1120, while the sum is 25.

The square root of 21115744 is about 4595.1870473355. The cubic root of 21115744 is about 276.3983605533.

Adding to 21115744 its reverse (44751112), we get a palindrome (65866856).

The spelling of 21115744 in words is "twenty-one million, one hundred fifteen thousand, seven hundred forty-four".