161881669 has 2 divisors, whose sum is σ = 161881670. Its totient is φ = 161881668.

The previous prime is 161881649. The next prime is 161881679. The reversal of 161881669 is 966188161.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 143089444 + 18792225 = 11962^2 + 4335^2 .

It is a cyclic number.

It is not a de Polignac number, because 161881669 - 2¹³ = 161873477 is a prime.

It is a super-2 number, since 2×161881669² = 52411349516451122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161881639) 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 as a sum of consecutive naturals, namely, 80940834 + 80940835.

It is an arithmetic number, because the mean of its divisors is an integer number (80940835).

Almost surely, 2^161881669 is an apocalyptic number.

It is an amenable number.

161881669 is a deficient number, since it is larger than the sum of its proper divisors (1).

161881669 is an equidigital number, since it uses as much as digits as its factorization.

161881669 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 124416, while the sum is 46.

The square root of 161881669 is about 12723.2727314948. The cubic root of 161881669 is about 545.0034160771.

The spelling of 161881669 in words is "one hundred sixty-one million, eight hundred eighty-one thousand, six hundred sixty-nine".