161691928318981 has 8 divisors (see below), whose sum is σ = 170789373649664. Its totient is φ = 152837081530560.

The previous prime is 161691928318891. The next prime is 161691928319003. The reversal of 161691928318981 is 189813829196161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161691928318981 - 2¹⁹ = 161691927794693 is a prime.

It is a super-2 number, since 2×161691928318981² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161691928318681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60649634196 + ... + 60649636861.

It is an arithmetic number, because the mean of its divisors is an integer number (21348671706208).

Almost surely, 2^{161691928318981} is an apocalyptic number.

It is an amenable number.

161691928318981 is a deficient number, since it is larger than the sum of its proper divisors (9097445330683).

161691928318981 is a wasteful number, since it uses less digits than its factorization.

161691928318981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121299271131.

The product of its digits is 80621568, while the sum is 73.

The spelling of 161691928318981 in words is "one hundred sixty-one trillion, six hundred ninety-one billion, nine hundred twenty-eight million, three hundred eighteen thousand, nine hundred eighty-one".