166666649 has 2 divisors, whose sum is σ = 166666650. Its totient is φ = 166666648.

The previous prime is 166666639. The next prime is 166666673. The reversal of 166666649 is 946666661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129846025 + 36820624 = 11395^2 + 6068^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166666649 is a prime.

It is a super-4 number, since 4×166666649⁴ (a number of 34 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 166666597 and 166666606.

It is not a weakly prime, because it can be changed into another prime (166666639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83333324 + 83333325.

It is an arithmetic number, because the mean of its divisors is an integer number (83333325).

Almost surely, 2^166666649 is an apocalyptic number.

It is an amenable number.

166666649 is a deficient number, since it is larger than the sum of its proper divisors (1).

166666649 is an equidigital number, since it uses as much as digits as its factorization.

166666649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1679616, while the sum is 50.

The square root of 166666649 is about 12909.9438031310. The cubic root of 166666649 is about 550.3211887044.

The spelling of 166666649 in words is "one hundred sixty-six million, six hundred sixty-six thousand, six hundred forty-nine".