1666663779 has 32 divisors (see below), whose sum is σ = 2513223936. Its totient is φ = 973537920.

The previous prime is 1666663771. The next prime is 1666663807. The reversal of 1666663779 is 9773666661.

It is not a de Polignac number, because 1666663779 - 2³ = 1666663771 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666663771) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 124269 + ... + 137025.

It is an arithmetic number, because the mean of its divisors is an integer number (78538248).

Almost surely, 2^1666663779 is an apocalyptic number.

1666663779 is a deficient number, since it is larger than the sum of its proper divisors (846560157).

1666663779 is a wasteful number, since it uses less digits than its factorization.

1666663779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12915.

The product of its digits is 10287648, while the sum is 57.

The square root of 1666663779 is about 40824.7936798216. The cubic root of 1666663779 is about 1185.6304167548.

The spelling of 1666663779 in words is "one billion, six hundred sixty-six million, six hundred sixty-three thousand, seven hundred seventy-nine".