21242 has 16 divisors (see below), whose sum is σ = 36960. Its totient is φ = 9072.

The previous prime is 21227. The next prime is 21247. The reversal of 21242 is 24212.

It is not an unprimeable number, because it can be changed into a prime (21247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 473 + ... + 515.

It is an arithmetic number, because the mean of its divisors is an integer number (2310).

2²¹²⁴² is an apocalyptic number.

21242 is a deficient number, since it is larger than the sum of its proper divisors (15718).

21242 is a wasteful number, since it uses less digits than its factorization.

21242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77.

The product of its digits is 32, while the sum is 11.

The square root of 21242 is about 145.7463550145. The cubic root of 21242 is about 27.6948149835.

Adding to 21242 its reverse (24212), we get a palindrome (45454).

The spelling of 21242 in words is "twenty-one thousand, two hundred forty-two", and thus it is an iban number.