19808749 has 4 divisors (see below), whose sum is σ = 19823836. Its totient is φ = 19793664.

The previous prime is 19808743. The next prime is 19808759. The reversal of 19808749 is 94780891.

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 17280649 + 2528100 = 4157^2 + 1590^2 .

It is a cyclic number.

It is not a de Polignac number, because 19808749 - 2³ = 19808741 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19808699 and 19808708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19808741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5364 + ... + 8269.

It is an arithmetic number, because the mean of its divisors is an integer number (4955959).

Almost surely, 2^19808749 is an apocalyptic number.

It is an amenable number.

19808749 is a deficient number, since it is larger than the sum of its proper divisors (15087).

19808749 is a wasteful number, since it uses less digits than its factorization.

19808749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15086.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 19808749 is about 4450.7020794477. The cubic root of 19808749 is about 270.5737638550.

The spelling of 19808749 in words is "nineteen million, eight hundred eight thousand, seven hundred forty-nine".