161981620842 has 16 divisors (see below), whose sum is σ = 325753096032. Its totient is φ = 53695564560.

The previous prime is 161981620813. The next prime is 161981620861. The reversal of 161981620842 is 248026189161.

It is a junction number, because it is equal to n+sod(n) for n = 161981620791 and 161981620800.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74576088 + ... + 74578259.

It is an arithmetic number, because the mean of its divisors is an integer number (20359568502).

Almost surely, 2^161981620842 is an apocalyptic number.

161981620842 is an abundant number, since it is smaller than the sum of its proper divisors (163771475190).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161981620842 is a wasteful number, since it uses less digits than its factorization.

161981620842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149154533.

The product of its (nonzero) digits is 331776, while the sum is 48.

The spelling of 161981620842 in words is "one hundred sixty-one billion, nine hundred eighty-one million, six hundred twenty thousand, eight hundred forty-two".