20718985 has 16 divisors (see below), whose sum is σ = 28509696. Its totient is φ = 14159808.

The previous prime is 20718983. The next prime is 20718989. The reversal of 20718985 is 58981702.

It is a cyclic number.

It is not a de Polignac number, because 20718985 - 2¹ = 20718983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20718983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12039 + ... + 13651.

It is an arithmetic number, because the mean of its divisors is an integer number (1781856).

Almost surely, 2^20718985 is an apocalyptic number.

It is an amenable number.

20718985 is a deficient number, since it is larger than the sum of its proper divisors (7790711).

20718985 is a wasteful number, since it uses less digits than its factorization.

20718985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1992.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 20718985 is about 4551.8111779818. The cubic root of 20718985 is about 274.6562536964.

The spelling of 20718985 in words is "twenty million, seven hundred eighteen thousand, nine hundred eighty-five".