19717989 has 12 divisors (see below), whose sum is σ = 26562048. Its totient is φ = 13010920.

The previous prime is 19717987. The next prime is 19717993. The reversal of 19717989 is 98971791.

It is not a de Polignac number, because 19717989 - 2¹ = 19717987 is a prime.

Its product of digits (285768) is a multiple of the sum of its prime factors (648).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19717981) 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, 51292 + ... + 51674.

It is an arithmetic number, because the mean of its divisors is an integer number (2213504).

Almost surely, 2^19717989 is an apocalyptic number.

It is an amenable number.

19717989 is a deficient number, since it is larger than the sum of its proper divisors (6844059).

19717989 is an equidigital number, since it uses as much as digits as its factorization.

19717989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 648 (or 517 counting only the distinct ones).

The product of its digits is 285768, while the sum is 51.

The square root of 19717989 is about 4440.4942292497. The cubic root of 19717989 is about 270.1598915775.

It can be divided in two parts, 19717 and 989, that added together give a triangular number (20706 = T₂₀₃).

The spelling of 19717989 in words is "nineteen million, seven hundred seventeen thousand, nine hundred eighty-nine".