161640818009 has 32 divisors (see below), whose sum is σ = 182965636992. Its totient is φ = 142686878400.

The previous prime is 161640817997. The next prime is 161640818117. The reversal of 161640818009 is 900818046161.

It is not a de Polignac number, because 161640818009 - 2⁸ = 161640817753 is a prime.

It is a super-2 number, since 2×161640818009² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (161640818609) 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 31 ways as a sum of consecutive naturals, for example, 26639594 + ... + 26645660.

It is an arithmetic number, because the mean of its divisors is an integer number (5717676156).

Almost surely, 2^161640818009 is an apocalyptic number.

It is an amenable number.

161640818009 is a deficient number, since it is larger than the sum of its proper divisors (21324818983).

161640818009 is an equidigital number, since it uses as much as digits as its factorization.

161640818009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6678 (or 6656 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 44.

The spelling of 161640818009 in words is "one hundred sixty-one billion, six hundred forty million, eight hundred eighteen thousand, nine".