19985661 has 12 divisors (see below), whose sum is σ = 29648892. Its totient is φ = 12963456.

The previous prime is 19985627. The next prime is 19985671. The reversal of 19985661 is 16658991.

It can be written as a sum of positive squares in 2 ways, for example, as 17690436 + 2295225 = 4206^2 + 1515^2 .

It is not a de Polignac number, because 19985661 - 2⁷ = 19985533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19985621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29676 + ... + 30341.

It is an arithmetic number, because the mean of its divisors is an integer number (2470741).

Almost surely, 2^19985661 is an apocalyptic number.

It is an amenable number.

19985661 is a deficient number, since it is larger than the sum of its proper divisors (9663231).

19985661 is a wasteful number, since it uses less digits than its factorization.

19985661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60060 (or 60057 counting only the distinct ones).

The product of its digits is 116640, while the sum is 45.

The square root of 19985661 is about 4470.5325186157. The cubic root of 19985661 is about 271.3768760934.

The spelling of 19985661 in words is "nineteen million, nine hundred eighty-five thousand, six hundred sixty-one".