161858661 has 16 divisors (see below), whose sum is σ = 222082560. Its totient is φ = 104811200.

The previous prime is 161858651. The next prime is 161858677. The reversal of 161858661 is 166858161.

It is a cyclic number.

It is not a de Polignac number, because 161858661 - 2¹⁴ = 161842277 is a prime.

It is a super-2 number, since 2×161858661² = 52396452281425842, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161858651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11020 + ... + 21098.

It is an arithmetic number, because the mean of its divisors is an integer number (13880160).

Almost surely, 2^161858661 is an apocalyptic number.

It is an amenable number.

161858661 is a deficient number, since it is larger than the sum of its proper divisors (60223899).

161858661 is a wasteful number, since it uses less digits than its factorization.

161858661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10236.

The product of its digits is 69120, while the sum is 42.

The square root of 161858661 is about 12722.3685294838. The cubic root of 161858661 is about 544.9775946797.

The spelling of 161858661 in words is "one hundred sixty-one million, eight hundred fifty-eight thousand, six hundred sixty-one".