1666658779 has 2 divisors, whose sum is σ = 1666658780. Its totient is φ = 1666658778.

The previous prime is 1666658771. The next prime is 1666658803. The reversal of 1666658779 is 9778566661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666658779 - 2³ = 1666658771 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666658771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833329389 + 833329390.

It is an arithmetic number, because the mean of its divisors is an integer number (833329390).

Almost surely, 2^1666658779 is an apocalyptic number.

1666658779 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666658779 is an equidigital number, since it uses as much as digits as its factorization.

1666658779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22861440, while the sum is 61.

The square root of 1666658779 is about 40824.7324424790. The cubic root of 1666658779 is about 1185.6292311212.

The spelling of 1666658779 in words is "one billion, six hundred sixty-six million, six hundred fifty-eight thousand, seven hundred seventy-nine".