161666693 has 4 divisors (see below), whose sum is σ = 161813580. Its totient is φ = 161519808.

The previous prime is 161666669. The next prime is 161666711. The reversal of 161666693 is 396666161.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6340324 + 155326369 = 2518^2 + 12463^2 .

It is a cyclic number.

It is not a de Polignac number, because 161666693 - 2⁶ = 161666629 is a prime.

It is a super-2 number, since 2×161666693² = 52272239251112498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161666663) 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 3 ways as a sum of consecutive naturals, for example, 71780 + ... + 73997.

It is an arithmetic number, because the mean of its divisors is an integer number (40453395).

Almost surely, 2^161666693 is an apocalyptic number.

It is an amenable number.

161666693 is a deficient number, since it is larger than the sum of its proper divisors (146887).

161666693 is a wasteful number, since it uses less digits than its factorization.

161666693 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146886.

The product of its digits is 209952, while the sum is 44.

The square root of 161666693 is about 12714.8217840440. The cubic root of 161666693 is about 544.7620575657.

The spelling of 161666693 in words is "one hundred sixty-one million, six hundred sixty-six thousand, six hundred ninety-three".