21748 has 6 divisors (see below), whose sum is σ = 38066. Its totient is φ = 10872.

The previous prime is 21739. The next prime is 21751. The reversal of 21748 is 84712.

It can be written as a sum of positive squares in only one way, i.e., 19044 + 2704 = 138^2 + 52^2 .

It is a plaindrome in base 15.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2715 + ... + 2722.

2²¹⁷⁴⁸ is an apocalyptic number.

It is an amenable number.

21748 is a deficient number, since it is larger than the sum of its proper divisors (16318).

21748 is a wasteful number, since it uses less digits than its factorization.

21748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5441 (or 5439 counting only the distinct ones).

The product of its digits is 448, while the sum is 22.

The square root of 21748 is about 147.4720312466. The cubic root of 21748 is about 27.9129952351.

The spelling of 21748 in words is "twenty-one thousand, seven hundred forty-eight".