166661009 has 4 divisors (see below), whose sum is σ = 168311220. Its totient is φ = 165010800.

The previous prime is 166660969. The next prime is 166661029. The reversal of 166661009 is 900166661.

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 83905600 + 82755409 = 9160^2 + 9097^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166661009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 166661009.

It is not an unprimeable number, because it can be changed into a prime (166661029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 824954 + ... + 825155.

It is an arithmetic number, because the mean of its divisors is an integer number (42077805).

Almost surely, 2^166661009 is an apocalyptic number.

It is an amenable number.

166661009 is a deficient number, since it is larger than the sum of its proper divisors (1650211).

166661009 is a wasteful number, since it uses less digits than its factorization.

166661009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1650210.

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 166661009 is about 12909.7253650107. The cubic root of 166661009 is about 550.3149810107.

The spelling of 166661009 in words is "one hundred sixty-six million, six hundred sixty-one thousand, nine".