21744680 has 16 divisors (see below), whose sum is σ = 48925620. Its totient is φ = 8697856.

The previous prime is 21744631. The next prime is 21744727. The reversal of 21744680 is 8644712.

It can be written as a sum of positive squares in 2 ways, for example, as 20994724 + 749956 = 4582^2 + 866^2 .

It is a super-2 number, since 2×21744680² = 945662216604800, which contains 22 as substring.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 271769 + ... + 271848.

Almost surely, 2^21744680 is an apocalyptic number.

21744680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21744680 is an abundant number, since it is smaller than the sum of its proper divisors (27180940).

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

21744680 is a wasteful number, since it uses less digits than its factorization.

21744680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 543628 (or 543624 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 32.

The square root of 21744680 is about 4663.1191277942. The cubic root of 21744680 is about 279.1157478479.

Adding to 21744680 its sum of digits (32), we get a palindrome (21744712).

The spelling of 21744680 in words is "twenty-one million, seven hundred forty-four thousand, six hundred eighty".