21487744 has 16 divisors (see below), whose sum is σ = 42807870. Its totient is φ = 10743808.

The previous prime is 21487717. The next prime is 21487751. The reversal of 21487744 is 44778412.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 1345600 = 4488^2 + 1160^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83809 + ... + 84064.

Almost surely, 2^21487744 is an apocalyptic number.

It is an amenable number.

21487744 is a deficient number, since it is larger than the sum of its proper divisors (21320126).

21487744 is an equidigital number, since it uses as much as digits as its factorization.

21487744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167887 (or 167875 counting only the distinct ones).

The product of its digits is 50176, while the sum is 37.

The square root of 21487744 is about 4635.4874608826. The cubic root of 21487744 is about 278.0120416432.

The spelling of 21487744 in words is "twenty-one million, four hundred eighty-seven thousand, seven hundred forty-four".