Base | Representation |
---|---|
bin | 101000011100… |
… | …1010111110001 |
3 | 1110220101212102 |
4 | 1100321113301 |
5 | 20412102023 |
6 | 2034310145 |
7 | 345152366 |
oct | 120712761 |
9 | 43811772 |
10 | 21206513 |
11 | 10a74849 |
12 | 7128355 |
13 | 4516643 |
14 | 2b6046d |
15 | 1cdd628 |
hex | 14395f1 |
21206513 has 8 divisors (see below), whose sum is σ = 21912168. Its totient is φ = 20507904.
The previous prime is 21206509. The next prime is 21206533. The reversal of 21206513 is 31560212.
It can be written as a sum of positive squares in 4 ways, for example, as 17073424 + 4133089 = 4132^2 + 2033^2 .
It is a sphenic number, since it is the product of 3 distinct primes.
It is a cyclic number.
It is not a de Polignac number, because 21206513 - 22 = 21206509 is a prime.
It is a Duffinian number.
It is a Curzon number.
It is not an unprimeable number, because it can be changed into a prime (21206533) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (13) of ones.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4745 + ... + 8057.
It is an arithmetic number, because the mean of its divisors is an integer number (2739021).
Almost surely, 221206513 is an apocalyptic number.
It is an amenable number.
21206513 is a deficient number, since it is larger than the sum of its proper divisors (705655).
21206513 is a wasteful number, since it uses less digits than its factorization.
21206513 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 3523.
The product of its (nonzero) digits is 360, while the sum is 20.
The square root of 21206513 is about 4605.0529855801. The cubic root of 21206513 is about 276.7938401808.
Adding to 21206513 its reverse (31560212), we get a palindrome (52766725).
The spelling of 21206513 in words is "twenty-one million, two hundred six thousand, five hundred thirteen".
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