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21065 = 511383

21065 has 8 divisors (see below), whose sum is σ = 27648. Its totient is φ = 15280.

The previous prime is 21061. The next prime is 21067. The reversal of 21065 is 56012.

21065 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21065 - 22 = 21061 is a prime.

It is a Duffinian number.

21065 is strictly pandigital in base 6.

It is a Curzon number.

It is a nialpdrome in base 8.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21065.

It is not an unprimeable number, because it can be changed into a prime (21061) 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, 137 + ... + 246.

It is an arithmetic number, because the mean of its divisors is an integer number (3456).

221065 is an apocalyptic number.

It is an amenable number.

21065 is a deficient number, since it is larger than the sum of its proper divisors (6583).

21065 is a wasteful number, since it uses less digits than its factorization.

21065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21065 is about 145.1378654935. The cubic root of 21065 is about 27.6176775362.

Adding to 21065 its reverse (56012), we get a palindrome (77077).

The spelling of 21065 in words is "twenty-one thousand, sixty-five".

Divisors: 1 5 11 55 383 1915 4213 21065