166681819 has 4 divisors (see below), whose sum is σ = 168211120. Its totient is φ = 165152520.

The previous prime is 166681807. The next prime is 166681831. The reversal of 166681819 is 918186661.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (166681807) and next prime (166681831).

It is a cyclic number.

It is not a de Polignac number, because 166681819 - 2¹¹ = 166679771 is a prime.

It is a super-2 number, since 2×166681819² = 55565657570297522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166681859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 764487 + ... + 764704.

It is an arithmetic number, because the mean of its divisors is an integer number (42052780).

Almost surely, 2^166681819 is an apocalyptic number.

166681819 is a deficient number, since it is larger than the sum of its proper divisors (1529301).

166681819 is a wasteful number, since it uses less digits than its factorization.

166681819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1529300.

The product of its digits is 124416, while the sum is 46.

The square root of 166681819 is about 12910.5313213671. The cubic root of 166681819 is about 550.3378849445.

The spelling of 166681819 in words is "one hundred sixty-six million, six hundred eighty-one thousand, eight hundred nineteen".