19809985 has 16 divisors (see below), whose sum is σ = 26295696. Its totient is φ = 14231808.

The previous prime is 19809973. The next prime is 19809991. The reversal of 19809985 is 58990891.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 16384 + 19793601 = 128^2 + 4449^2 .

It is a cyclic number.

It is not a de Polignac number, because 19809985 - 2⁵ = 19809953 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 1714 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (1643481).

Almost surely, 2^19809985 is an apocalyptic number.

It is an amenable number.

19809985 is a deficient number, since it is larger than the sum of its proper divisors (6485711).

19809985 is a wasteful number, since it uses less digits than its factorization.

19809985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8292.

The product of its (nonzero) digits is 233280, while the sum is 49.

The square root of 19809985 is about 4450.8409317791. The cubic root of 19809985 is about 270.5793913721.

The spelling of 19809985 in words is "nineteen million, eight hundred nine thousand, nine hundred eighty-five".