21489 has 16 divisors (see below), whose sum is σ = 33600. Its totient is φ = 12096.
The previous prime is 21487. The next prime is 21491. The reversal of 21489 is 98412.
It is an interprime number because it is at equal distance from previous prime (21487) and next prime (21491).
It is not a de Polignac number, because 21489 - 21 = 21487 is a prime.
Its product of digits (576) is a multiple of the sum of its prime divisors (64).
It is a Curzon number.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21489.
It is not an unprimeable number, because it can be changed into a prime (21481) by changing a digit.
It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 727 + ... + 755.
It is an arithmetic number, because the mean of its divisors is an integer number (2100).
221489 is an apocalyptic number.
21489 is a gapful number since it is divisible by the number (29) formed by its first and last digit.
It is an amenable number.
21489 is a deficient number, since it is larger than the sum of its proper divisors (12111).
21489 is a wasteful number, since it uses less digits than its factorization.
21489 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 64.
The product of its digits is 576, while the sum is 24.
The square root of 21489 is about 146.5912684985. The cubic root of 21489 is about 27.8017458317.
It can be divided in two parts, 214 and 89, that added together give a palindrome (303).
The spelling of 21489 in words is "twenty-one thousand, four hundred eighty-nine".
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