1640834209 has 4 divisors (see below), whose sum is σ = 1875239104. Its totient is φ = 1406429316.

The previous prime is 1640834201. The next prime is 1640834219. The reversal of 1640834209 is 9024380461.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9024380461 = 1913 ⋅4717397.

It is a cyclic number.

It is not a de Polignac number, because 1640834209 - 2³ = 1640834201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1640834201) 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, 117202437 + ... + 117202450.

It is an arithmetic number, because the mean of its divisors is an integer number (468809776).

Almost surely, 2^1640834209 is an apocalyptic number.

It is an amenable number.

1640834209 is a deficient number, since it is larger than the sum of its proper divisors (234404895).

1640834209 is an equidigital number, since it uses as much as digits as its factorization.

1640834209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 234404894.

The product of its (nonzero) digits is 41472, while the sum is 37.

The square root of 1640834209 is about 40507.2118146880. The cubic root of 1640834209 is about 1179.4736254710.

The spelling of 1640834209 in words is "one billion, six hundred forty million, eight hundred thirty-four thousand, two hundred nine".