19428709 has 4 divisors (see below), whose sum is σ = 19459116. Its totient is φ = 19398304.

The previous prime is 19428691. The next prime is 19428743. The reversal of 19428709 is 90782491.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90782491 = 191 ⋅475301.

It can be written as a sum of positive squares in 2 ways, for example, as 13068225 + 6360484 = 3615^2 + 2522^2 .

It is a cyclic number.

It is not a de Polignac number, because 19428709 - 2⁹ = 19428197 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19428749) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14224 + ... + 15529.

It is an arithmetic number, because the mean of its divisors is an integer number (4864779).

Almost surely, 2^19428709 is an apocalyptic number.

It is an amenable number.

19428709 is a deficient number, since it is larger than the sum of its proper divisors (30407).

19428709 is an equidigital number, since it uses as much as digits as its factorization.

19428709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30406.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 19428709 is about 4407.8009256317. The cubic root of 19428709 is about 268.8322175708.

The spelling of 19428709 in words is "nineteen million, four hundred twenty-eight thousand, seven hundred nine".