21459744 has 72 divisors (see below), whose sum is σ = 61474140. Its totient is φ = 7100928.

The previous prime is 21459743. The next prime is 21459751. The reversal of 21459744 is 44795412.

It is a happy number.

21459744 is a `hidden beast` number, since 21 + 4 + 597 + 44 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 17539344 + 3920400 = 4188^2 + 1980^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×21459744² = 921041225091072, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21459699 and 21459708.

It is not an unprimeable number, because it can be changed into a prime (21459743) 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 11 ways as a sum of consecutive naturals, for example, 77334 + ... + 77610.

Almost surely, 2^21459744 is an apocalyptic number.

21459744 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 21459744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30737070).

21459744 is an abundant number, since it is smaller than the sum of its proper divisors (40014396).

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

21459744 is a wasteful number, since it uses less digits than its factorization.

21459744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 551 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21459744 is about 4632.4662977727. The cubic root of 21459744 is about 277.8912329194.

The spelling of 21459744 in words is "twenty-one million, four hundred fifty-nine thousand, seven hundred forty-four".