20436 has 24 divisors (see below), whose sum is σ = 51744. Its totient is φ = 6240.

The previous prime is 20431. The next prime is 20441. The reversal of 20436 is 63402.

It is an interprime number because it is at equal distance from previous prime (20431) and next prime (20441).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20431) by changing a digit.

20436 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91 + ... + 221.

It is an arithmetic number, because the mean of its divisors is an integer number (2156).

2²⁰⁴³⁶ is an apocalyptic number.

20436 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20436, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25872).

20436 is an abundant number, since it is smaller than the sum of its proper divisors (31308).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20436 is a wasteful number, since it uses less digits than its factorization.

20436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 20436 is about 142.9545382281. The cubic root of 20436 is about 27.3400076239.

Adding to 20436 its reverse (63402), we get a palindrome (83838).

The spelling of 20436 in words is "twenty thousand, four hundred thirty-six".