20642 has 4 divisors (see below), whose sum is σ = 30966. Its totient is φ = 10320.

The previous prime is 20641. The next prime is 20663. The reversal of 20642 is 24602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24602 = 2 ⋅12301.

It can be written as a sum of positive squares in only one way, i.e., 17161 + 3481 = 131^2 + 59^2 .

It is a plaindrome in base 11.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5159 + ... + 5162.

2²⁰⁶⁴² is an apocalyptic number.

20642 is a deficient number, since it is larger than the sum of its proper divisors (10324).

20642 is a wasteful number, since it uses less digits than its factorization.

20642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10323.

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 20642 is about 143.6732403755. The cubic root of 20642 is about 27.4315653767.

The spelling of 20642 in words is "twenty thousand, six hundred forty-two".