21548 has 6 divisors (see below), whose sum is σ = 37716. Its totient is φ = 10772.

The previous prime is 21529. The next prime is 21557. The reversal of 21548 is 84512.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2690 + ... + 2697.

It is an arithmetic number, because the mean of its divisors is an integer number (6286).

2²¹⁵⁴⁸ is an apocalyptic number.

It is an amenable number.

21548 is a deficient number, since it is larger than the sum of its proper divisors (16168).

21548 is a wasteful number, since it uses less digits than its factorization.

21548 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5391 (or 5389 counting only the distinct ones).

The product of its digits is 320, while the sum is 20.

The square root of 21548 is about 146.7923703739. The cubic root of 21548 is about 27.8271666531.

Subtracting from 21548 its sum of digits (20), we obtain a triangular number (21528 = T₂₀₇).

The spelling of 21548 in words is "twenty-one thousand, five hundred forty-eight".