20915 has 8 divisors (see below), whose sum is σ = 25920. Its totient is φ = 16192.

The previous prime is 20903. The next prime is 20921. The reversal of 20915 is 51902.

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 20915 - 2⁴ = 20899 is a prime.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 20893 and 20902.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191 + ... + 279.

It is an arithmetic number, because the mean of its divisors is an integer number (3240).

2²⁰⁹¹⁵ is an apocalyptic number.

20915 is a deficient number, since it is larger than the sum of its proper divisors (5005).

20915 is an equidigital number, since it uses as much as digits as its factorization.

20915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141.

The product of its (nonzero) digits is 90, while the sum is 17.

The square root of 20915 is about 144.6201922278. The cubic root of 20915 is about 27.5519678481.

The spelling of 20915 in words is "twenty thousand, nine hundred fifteen".