19689749 has 4 divisors (see below), whose sum is σ = 19736940. Its totient is φ = 19642560.

The previous prime is 19689731. The next prime is 19689751. The reversal of 19689749 is 94798691.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1456849 + 18232900 = 1207^2 + 4270^2 .

It is a cyclic number.

It is not a de Polignac number, because 19689749 - 2⁸ = 19689493 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 19689749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19289749) 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 3 ways as a sum of consecutive naturals, for example, 22964 + ... + 23805.

It is an arithmetic number, because the mean of its divisors is an integer number (4934235).

Almost surely, 2^19689749 is an apocalyptic number.

It is an amenable number.

19689749 is a deficient number, since it is larger than the sum of its proper divisors (47191).

19689749 is an equidigital number, since it uses as much as digits as its factorization.

19689749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47190.

The product of its digits is 979776, while the sum is 53.

The square root of 19689749 is about 4437.3132636766. The cubic root of 19689749 is about 270.0308560986.

The spelling of 19689749 in words is "nineteen million, six hundred eighty-nine thousand, seven hundred forty-nine".