1666320287 has 2 divisors, whose sum is σ = 1666320288. Its totient is φ = 1666320286.

The previous prime is 1666320259. The next prime is 1666320289. The reversal of 1666320287 is 7820236661.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1666320287 is a prime.

Together with 1666320289, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666320289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833160143 + 833160144.

It is an arithmetic number, because the mean of its divisors is an integer number (833160144).

Almost surely, 2^1666320287 is an apocalyptic number.

1666320287 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666320287 is an equidigital number, since it uses as much as digits as its factorization.

1666320287 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 1666320287 is about 40820.5865587451. The cubic root of 1666320287 is about 1185.5489601049.

The spelling of 1666320287 in words is "one billion, six hundred sixty-six million, three hundred twenty thousand, two hundred eighty-seven".