1666682181 has 12 divisors (see below), whose sum is σ = 2458652352. Its totient is φ = 1087480296.

The previous prime is 1666682179. The next prime is 1666682201. The reversal of 1666682181 is 1812866661.

It is not a de Polignac number, because 1666682181 - 2¹ = 1666682179 is a prime.

It is a super-2 number, since 2×1666682181² = 5555658984925833522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666682111) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1969651 + ... + 1970496.

It is an arithmetic number, because the mean of its divisors is an integer number (204887696).

Almost surely, 2^1666682181 is an apocalyptic number.

It is an amenable number.

1666682181 is a deficient number, since it is larger than the sum of its proper divisors (791970171).

1666682181 is a wasteful number, since it uses less digits than its factorization.

1666682181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3940200 (or 3940197 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 1666682181 is about 40825.0190569460. The cubic root of 1666682181 is about 1185.6347803405.

The spelling of 1666682181 in words is "one billion, six hundred sixty-six million, six hundred eighty-two thousand, one hundred eighty-one".