20663985 has 16 divisors (see below), whose sum is σ = 33257664. Its totient is φ = 10955712.

The previous prime is 20663977. The next prime is 20663987. The reversal of 20663985 is 58936602.

It is not a de Polignac number, because 20663985 - 2³ = 20663977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20663987) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1387 + ... + 6576.

It is an arithmetic number, because the mean of its divisors is an integer number (2078604).

Almost surely, 2^20663985 is an apocalyptic number.

It is an amenable number.

20663985 is a deficient number, since it is larger than the sum of its proper divisors (12593679).

20663985 is a wasteful number, since it uses less digits than its factorization.

20663985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8144.

The product of its (nonzero) digits is 77760, while the sum is 39.

The square root of 20663985 is about 4545.7656120834. The cubic root of 20663985 is about 274.4130068959.

The spelling of 20663985 in words is "twenty million, six hundred sixty-three thousand, nine hundred eighty-five".