21142 has 12 divisors (see below), whose sum is σ = 35748. Its totient is φ = 9300.

The previous prime is 21139. The next prime is 21143. The reversal of 21142 is 24112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21143) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 667 + ... + 697.

It is an arithmetic number, because the mean of its divisors is an integer number (2979).

2²¹¹⁴² is an apocalyptic number.

21142 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21142 is a deficient number, since it is larger than the sum of its proper divisors (14606).

21142 is a wasteful number, since it uses less digits than its factorization.

21142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75 (or 44 counting only the distinct ones).

The product of its digits is 16, while the sum is 10.

The square root of 21142 is about 145.4028885545. The cubic root of 21142 is about 27.6512873994.

Adding to 21142 its reverse (24112), we get a palindrome (45254).

It can be divided in two parts, 2114 and 2, that added together give a square (2116 = 46²).

The spelling of 21142 in words is "twenty-one thousand, one hundred forty-two", and thus it is an iban number.