1666349987 has 2 divisors, whose sum is σ = 1666349988. Its totient is φ = 1666349986.

The previous prime is 1666349983. The next prime is 1666350017. The reversal of 1666349987 is 7899436661.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666349987 - 2² = 1666349983 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666349981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833174993 + 833174994.

It is an arithmetic number, because the mean of its divisors is an integer number (833174994).

Almost surely, 2^1666349987 is an apocalyptic number.

1666349987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666349987 is an equidigital number, since it uses as much as digits as its factorization.

1666349987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11757312, while the sum is 59.

The square root of 1666349987 is about 40820.9503441554. The cubic root of 1666349987 is about 1185.5560036877.

The spelling of 1666349987 in words is "one billion, six hundred sixty-six million, three hundred forty-nine thousand, nine hundred eighty-seven".