20501 has 8 divisors (see below), whose sum is σ = 23520. Its totient is φ = 17712.

The previous prime is 20483. The next prime is 20507. The reversal of 20501 is 10502.

20501 = T₂₆ + T₂₇ + ... + T₅₁.

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

It is a cyclic number.

It is not a de Polignac number, because 20501 - 2¹⁰ = 19477 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a nialpdrome in base 13.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20507) 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 in 7 ways as a sum of consecutive naturals, for example, 206 + ... + 288.

It is an arithmetic number, because the mean of its divisors is an integer number (2940).

2²⁰⁵⁰¹ is an apocalyptic number.

20501 is the 83-rd octagonal number.

It is an amenable number.

20501 is a deficient number, since it is larger than the sum of its proper divisors (3019).

20501 is a wasteful number, since it uses less digits than its factorization.

20501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115.

The product of its (nonzero) digits is 10, while the sum is 8.

The square root of 20501 is about 143.1817027417. The cubic root of 20501 is about 27.3689633833.

Subtracting from 20501 its reverse (10502), we obtain a palindrome (9999).

The spelling of 20501 in words is "twenty thousand, five hundred one".