19661689 has 8 divisors (see below), whose sum is σ = 20343680. Its totient is φ = 18987696.

The previous prime is 19661671. The next prime is 19661693. The reversal of 19661689 is 98616691.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19661689 - 2¹⁹ = 19137401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19661699) 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 7 ways as a sum of consecutive naturals, for example, 3232 + ... + 7054.

It is an arithmetic number, because the mean of its divisors is an integer number (2542960).

Almost surely, 2^19661689 is an apocalyptic number.

It is an amenable number.

19661689 is a deficient number, since it is larger than the sum of its proper divisors (681991).

19661689 is a wasteful number, since it uses less digits than its factorization.

19661689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3999.

The product of its digits is 139968, while the sum is 46.

The square root of 19661689 is about 4434.1503131942. The cubic root of 19661689 is about 269.9025208237.

It can be divided in two parts, 1966 and 1689, that added together give a triangular number (3655 = T₈₅).

The spelling of 19661689 in words is "nineteen million, six hundred sixty-one thousand, six hundred eighty-nine".