161766218 has 4 divisors (see below), whose sum is σ = 242649330. Its totient is φ = 80883108.

The previous prime is 161766211. The next prime is 161766251. The reversal of 161766218 is 812667161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 812667161 = 2837 ⋅286453.

It can be written as a sum of positive squares in only one way, i.e., 137194369 + 24571849 = 11713^2 + 4957^2 .

It is not an unprimeable number, because it can be changed into a prime (161766211) 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, 40441553 + ... + 40441556.

Almost surely, 2^161766218 is an apocalyptic number.

161766218 is a deficient number, since it is larger than the sum of its proper divisors (80883112).

161766218 is an equidigital number, since it uses as much as digits as its factorization.

161766218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80883111.

The product of its digits is 24192, while the sum is 38.

The square root of 161766218 is about 12718.7349213670. The cubic root of 161766218 is about 544.8738231595.

The spelling of 161766218 in words is "one hundred sixty-one million, seven hundred sixty-six thousand, two hundred eighteen".