1666440187 has 2 divisors, whose sum is σ = 1666440188. Its totient is φ = 1666440186.

The previous prime is 1666440173. The next prime is 1666440199. The reversal of 1666440187 is 7810446661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1666440187 - 2²³ = 1658051579 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666440157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833220093 + 833220094.

It is an arithmetic number, because the mean of its divisors is an integer number (833220094).

Almost surely, 2^1666440187 is an apocalyptic number.

1666440187 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666440187 is an equidigital number, since it uses as much as digits as its factorization.

1666440187 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 43.

The square root of 1666440187 is about 40822.0551540463. The cubic root of 1666440187 is about 1185.5773947966.

The spelling of 1666440187 in words is "one billion, six hundred sixty-six million, four hundred forty thousand, one hundred eighty-seven".