1666866787 has 16 divisors (see below), whose sum is σ = 1767439872. Its totient is φ = 1568730240.

The previous prime is 1666866769. The next prime is 1666866809. The reversal of 1666866787 is 7876686661.

It is a cyclic number.

It is not a de Polignac number, because 1666866787 - 2¹⁵ = 1666834019 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666866587) 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 in 15 ways as a sum of consecutive naturals, for example, 1284523 + ... + 1285819.

It is an arithmetic number, because the mean of its divisors is an integer number (110464992).

Almost surely, 2^1666866787 is an apocalyptic number.

1666866787 is a deficient number, since it is larger than the sum of its proper divisors (100573085).

1666866787 is a wasteful number, since it uses less digits than its factorization.

1666866787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2178.

The product of its digits is 24385536, while the sum is 61.

The square root of 1666866787 is about 40827.2799363367. The cubic root of 1666866787 is about 1185.6785533758.

The spelling of 1666866787 in words is "one billion, six hundred sixty-six million, eight hundred sixty-six thousand, seven hundred eighty-seven".