20015 has 4 divisors (see below), whose sum is σ = 24024. Its totient is φ = 16008.

The previous prime is 20011. The next prime is 20021. The reversal of 20015 is 51002.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20015 - 2² = 20011 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19984 and 20011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1997 + ... + 2006.

It is an arithmetic number, because the mean of its divisors is an integer number (6006).

2²⁰⁰¹⁵ is an apocalyptic number.

20015 is a deficient number, since it is larger than the sum of its proper divisors (4009).

20015 is an equidigital number, since it uses as much as digits as its factorization.

20015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4008.

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

The square root of 20015 is about 141.4743793059. The cubic root of 20015 is about 27.1509605142.

Adding to 20015 its reverse (51002), we get a palindrome (71017).

The spelling of 20015 in words is "twenty thousand, fifteen".