161803650881 has 4 divisors (see below), whose sum is σ = 161846929200. Its totient is φ = 161760372564.

The previous prime is 161803650839. The next prime is 161803650893. The reversal of 161803650881 is 188056308161.

It is a happy number.

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: 188056308161 = 19469 ⋅9659269.

It is a cyclic number.

It is not a de Polignac number, because 161803650881 - 2³⁰ = 160729909057 is a prime.

It is a super-2 number, since 2×161803650881² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161803650581) 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, 21633551 + ... + 21641028.

It is an arithmetic number, because the mean of its divisors is an integer number (40461732300).

Almost surely, 2^161803650881 is an apocalyptic number.

It is an amenable number.

161803650881 is a deficient number, since it is larger than the sum of its proper divisors (43278319).

161803650881 is an equidigital number, since it uses as much as digits as its factorization.

161803650881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43278318.

The product of its (nonzero) digits is 276480, while the sum is 47.

The spelling of 161803650881 in words is "one hundred sixty-one billion, eight hundred three million, six hundred fifty thousand, eight hundred eighty-one".