21098 has 16 divisors (see below), whose sum is σ = 39744. Its totient is φ = 8160.
The previous prime is 21089. The next prime is 21101. The reversal of 21098 is 89012.
It is an alternating number because its digits alternate between even and odd.
It is a Curzon number.
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 7 ways as a sum of consecutive naturals, for example, 86 + ... + 222.
It is an arithmetic number, because the mean of its divisors is an integer number (2484).
221098 is an apocalyptic number.
21098 is a deficient number, since it is larger than the sum of its proper divisors (18646).
21098 is a wasteful number, since it uses less digits than its factorization.
21098 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 157.
The product of its (nonzero) digits is 144, while the sum is 20.
The square root of 21098 is about 145.2515060163. The cubic root of 21098 is about 27.6320917755.
The spelling of 21098 in words is "twenty-one thousand, ninety-eight".
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