21442 has 8 divisors (see below), whose sum is σ = 32832. Its totient is φ = 10500.

The previous prime is 21433. The next prime is 21467. The reversal of 21442 is 24412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67 + ... + 217.

It is an arithmetic number, because the mean of its divisors is an integer number (4104).

2²¹⁴⁴² is an apocalyptic number.

21442 is a deficient number, since it is larger than the sum of its proper divisors (11390).

21442 is a wasteful number, since it uses less digits than its factorization.

21442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 224.

The product of its digits is 64, while the sum is 13.

The square root of 21442 is about 146.4308710621. The cubic root of 21442 is about 27.7814620298.

Adding to 21442 its reverse (24412), we get a palindrome (45854).

It can be divided in two parts, 214 and 42, that added together give a 8-th power (256 = 2⁸).

The spelling of 21442 in words is "twenty-one thousand, four hundred forty-two", and thus it is an iban number.