1639944809 has 16 divisors (see below), whose sum is σ = 1724328000. Its totient is φ = 1557630144.

The previous prime is 1639944743. The next prime is 1639944829. The reversal of 1639944809 is 9084499361.

It is a cyclic number.

It is not a de Polignac number, because 1639944809 - 2¹⁶ = 1639879273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1639944829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 460574 + ... + 464120.

It is an arithmetic number, because the mean of its divisors is an integer number (107770500).

Almost surely, 2^1639944809 is an apocalyptic number.

It is an amenable number.

1639944809 is a deficient number, since it is larger than the sum of its proper divisors (84383191).

1639944809 is a wasteful number, since it uses less digits than its factorization.

1639944809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3832.

The product of its (nonzero) digits is 1679616, while the sum is 53.

The square root of 1639944809 is about 40496.2320345980. The cubic root of 1639944809 is about 1179.2604791271.

The spelling of 1639944809 in words is "one billion, six hundred thirty-nine million, nine hundred forty-four thousand, eight hundred nine".