20653 has 4 divisors (see below), whose sum is σ = 21760. Its totient is φ = 19548.

The previous prime is 20641. The next prime is 20663. The reversal of 20653 is 35602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20653 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a nialpdrome in base 12 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20663) 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, 525 + ... + 562.

It is an arithmetic number, because the mean of its divisors is an integer number (5440).

2²⁰⁶⁵³ is an apocalyptic number.

It is an amenable number.

20653 is a deficient number, since it is larger than the sum of its proper divisors (1107).

20653 is a wasteful number, since it uses less digits than its factorization.

20653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1106.

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

The square root of 20653 is about 143.7115165879. The cubic root of 20653 is about 27.4364372179.

The spelling of 20653 in words is "twenty thousand, six hundred fifty-three".