20815985 has 8 divisors (see below), whose sum is σ = 25280640. Its totient is φ = 16451824.

The previous prime is 20815981. The next prime is 20816009. The reversal of 20815985 is 58951802.

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 20815985 - 2² = 20815981 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20815981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24665 + ... + 25494.

It is an arithmetic number, because the mean of its divisors is an integer number (3160080).

Almost surely, 2^20815985 is an apocalyptic number.

It is an amenable number.

20815985 is a deficient number, since it is larger than the sum of its proper divisors (4464655).

20815985 is an equidigital number, since it uses as much as digits as its factorization.

20815985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50247.

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 20815985 is about 4562.4538353829. The cubic root of 20815985 is about 275.0842056184.

The spelling of 20815985 in words is "twenty million, eight hundred fifteen thousand, nine hundred eighty-five".