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21140 has 24 divisors (see below), whose sum is σ = 51072. Its totient is φ = 7200.

The previous prime is 21139. The next prime is 21143. The reversal of 21140 is 4112.

Adding to 21140 its reverse (4112), we get a palindrome (25252).

It can be divided in two parts, 21 and 140, that added together give a palindrome (161).

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 polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65 + ... + 215.

It is an arithmetic number, because the mean of its divisors is an integer number (2128).

221140 is an apocalyptic number.

21140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25536).

21140 is an abundant number, since it is smaller than the sum of its proper divisors (29932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21140 is a wasteful number, since it uses less digits than its factorization.

21140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167 (or 165 counting only the distinct ones).

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

The square root of 21140 is about 145.3960109494. The cubic root of 21140 is about 27.6504154492.

The spelling of 21140 in words is "twenty-one thousand, one hundred forty", and thus it is an iban number.