6436940807809 has 4 divisors (see below), whose sum is σ = 6437401821616. Its totient is φ = 6436479794004.

The previous prime is 6436940807783. The next prime is 6436940807837. The reversal of 6436940807809 is 9087080496346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6436940807809 - 2⁵ = 6436940807777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6436940807839) 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, 230485959 + ... + 230513884.

It is an arithmetic number, because the mean of its divisors is an integer number (1609350455404).

Almost surely, 2^{6436940807809} is an apocalyptic number.

It is an amenable number.

6436940807809 is a deficient number, since it is larger than the sum of its proper divisors (461013807).

6436940807809 is a wasteful number, since it uses less digits than its factorization.

6436940807809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461013806.

The product of its (nonzero) digits is 62705664, while the sum is 64.

The spelling of 6436940807809 in words is "six trillion, four hundred thirty-six billion, nine hundred forty million, eight hundred seven thousand, eight hundred nine".