20635 has 4 divisors (see below), whose sum is σ = 24768. Its totient is φ = 16504.

The previous prime is 20627. The next prime is 20639. The reversal of 20635 is 53602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 53602 = 2 ⋅26801.

It is a cyclic number.

It is not a de Polignac number, because 20635 - 2³ = 20627 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (20639) 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 in 3 ways as a sum of consecutive naturals, for example, 2059 + ... + 2068.

It is an arithmetic number, because the mean of its divisors is an integer number (6192).

2²⁰⁶³⁵ is an apocalyptic number.

20635 is a deficient number, since it is larger than the sum of its proper divisors (4133).

20635 is an equidigital number, since it uses as much as digits as its factorization.

20635 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4132.

The product of its (nonzero) digits is 180, while the sum is 16.

The square root of 20635 is about 143.6488774756. The cubic root of 20635 is about 27.4284642130.

The spelling of 20635 in words is "twenty thousand, six hundred thirty-five".