1666500243 has 4 divisors (see below), whose sum is σ = 2222000328. Its totient is φ = 1111000160.

The previous prime is 1666500233. The next prime is 1666500271. The reversal of 1666500243 is 3420056661.

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

It is a cyclic number.

It is not a de Polignac number, because 1666500243 - 2²⁹ = 1129629331 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666500233) 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, 277750038 + ... + 277750043.

It is an arithmetic number, because the mean of its divisors is an integer number (555500082).

Almost surely, 2^1666500243 is an apocalyptic number.

1666500243 is a deficient number, since it is larger than the sum of its proper divisors (555500085).

1666500243 is an equidigital number, since it uses as much as digits as its factorization.

1666500243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 555500084.

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 1666500243 is about 40822.7907301791. The cubic root of 1666500243 is about 1185.5916367680.

The spelling of 1666500243 in words is "one billion, six hundred sixty-six million, five hundred thousand, two hundred forty-three".