21230 has 16 divisors (see below), whose sum is σ = 41904. Its totient is φ = 7680.

The previous prime is 21227. The next prime is 21247. The reversal of 21230 is 3212.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a nialpdrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14 + ... + 206.

It is an arithmetic number, because the mean of its divisors is an integer number (2619).

2²¹²³⁰ is an apocalyptic number.

21230 is a deficient number, since it is larger than the sum of its proper divisors (20674).

21230 is a wasteful number, since it uses less digits than its factorization.

21230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211.

The product of its (nonzero) digits is 12, while the sum is 8.

The square root of 21230 is about 145.7051817884. The cubic root of 21230 is about 27.6895988962.

Adding to 21230 its reverse (3212), we get a palindrome (24442).

It can be divided in two parts, 212 and 30, that added together give a palindrome (242).

The spelling of 21230 in words is "twenty-one thousand, two hundred thirty".