1666500081 has 8 divisors (see below), whose sum is σ = 2223191424. Its totient is φ = 1110404400.

The previous prime is 1666500079. The next prime is 1666500161. The reversal of 1666500081 is 1800056661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1666500081 - 2¹ = 1666500079 is a prime.

It is a super-2 number, since 2×1666500081² = 5554445039946013122, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1666500071) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 142345 + ... + 153606.

It is an arithmetic number, because the mean of its divisors is an integer number (277898928).

Almost surely, 2^1666500081 is an apocalyptic number.

It is an amenable number.

1666500081 is a deficient number, since it is larger than the sum of its proper divisors (556691343).

1666500081 is a wasteful number, since it uses less digits than its factorization.

1666500081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297831.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 1666500081 is about 40822.7887459933. The cubic root of 1666500081 is about 1185.5915983510.

The spelling of 1666500081 in words is "one billion, six hundred sixty-six million, five hundred thousand, eighty-one".