19640609 has 4 divisors (see below), whose sum is σ = 19861380. Its totient is φ = 19419840.

The previous prime is 19640603. The next prime is 19640633. The reversal of 19640609 is 90604691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90604691 = 163 ⋅555857.

It can be written as a sum of positive squares in 2 ways, for example, as 10061584 + 9579025 = 3172^2 + 3095^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19640609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19640603) 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, 110252 + ... + 110429.

It is an arithmetic number, because the mean of its divisors is an integer number (4965345).

Almost surely, 2^19640609 is an apocalyptic number.

It is an amenable number.

19640609 is a deficient number, since it is larger than the sum of its proper divisors (220771).

19640609 is an equidigital number, since it uses as much as digits as its factorization.

19640609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220770.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 19640609 is about 4431.7726701626. The cubic root of 19640609 is about 269.8060289494.

The spelling of 19640609 in words is "nineteen million, six hundred forty thousand, six hundred nine".