20899 has 2 divisors, whose sum is σ = 20900. Its totient is φ = 20898.
The previous prime is 20897. The next prime is 20903. The reversal of 20899 is 99802.
It is a happy number.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 20899 - 21 = 20897 is a prime.
Together with 20897, it forms a pair of twin primes.
It is a Chen prime.
20899 is a lucky number.
It is a plaindrome in base 11 and base 14.
It is not a weakly prime, because it can be changed into another prime (20897) 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 as a sum of consecutive naturals, namely, 10449 + 10450.
It is an arithmetic number, because the mean of its divisors is an integer number (10450).
220899 is an apocalyptic number.
20899 is a deficient number, since it is larger than the sum of its proper divisors (1).
20899 is an equidigital number, since it uses as much as digits as its factorization.
20899 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 1296, while the sum is 28.
The square root of 20899 is about 144.5648643343. The cubic root of 20899 is about 27.5449402930.
It can be divided in two parts, 20 and 899, that added together give a palindrome (919).
The spelling of 20899 in words is "twenty thousand, eight hundred ninety-nine".
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