161666197722 has 12 divisors (see below), whose sum is σ = 350276761770. Its totient is φ = 53888732568.

The previous prime is 161666197709. The next prime is 161666197733. The reversal of 161666197722 is 227791666161.

It can be written as a sum of positive squares in only one way, i.e., 98785118601 + 62881079121 = 314301^2 + 250761^2 .

It is a super-2 number, since 2×161666197722² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 4490727697 + ... + 4490727732.

Almost surely, 2^161666197722 is an apocalyptic number.

161666197722 is an abundant number, since it is smaller than the sum of its proper divisors (188610564048).

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

161666197722 is a wasteful number, since it uses less digits than its factorization.

161666197722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8981455437 (or 8981455434 counting only the distinct ones).

The product of its digits is 2286144, while the sum is 54.

The spelling of 161666197722 in words is "one hundred sixty-one billion, six hundred sixty-six million, one hundred ninety-seven thousand, seven hundred twenty-two".