161660666 has 4 divisors (see below), whose sum is σ = 242491002. Its totient is φ = 80830332.

The previous prime is 161660641. The next prime is 161660671. The reversal of 161660666 is 666066161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 119137225 + 42523441 = 10915^2 + 6521^2 .

It is a super-2 number, since 2×161660666² = 52268341863127112, which 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 as a sum of consecutive naturals, namely, 40415165 + ... + 40415168.

Almost surely, 2^161660666 is an apocalyptic number.

161660666 is a deficient number, since it is larger than the sum of its proper divisors (80830336).

161660666 is an equidigital number, since it uses as much as digits as its factorization.

161660666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80830335.

The product of its (nonzero) digits is 46656, while the sum is 38.

The square root of 161660666 is about 12714.5847749740. The cubic root of 161660666 is about 544.7552878313.

The spelling of 161660666 in words is "one hundred sixty-one million, six hundred sixty thousand, six hundred sixty-six".