1666768978 has 16 divisors (see below), whose sum is σ = 3025396224. Its totient is φ = 672310080.

The previous prime is 1666768951. The next prime is 1666769009. The reversal of 1666768978 is 8798676661.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3501378 + ... + 3501853.

It is an arithmetic number, because the mean of its divisors is an integer number (189087264).

Almost surely, 2^1666768978 is an apocalyptic number.

1666768978 is a deficient number, since it is larger than the sum of its proper divisors (1358627246).

1666768978 is a wasteful number, since it uses less digits than its factorization.

1666768978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003257.

The product of its digits is 36578304, while the sum is 64.

The square root of 1666768978 is about 40826.0820799645. The cubic root of 1666768978 is about 1185.6553617000.

The spelling of 1666768978 in words is "one billion, six hundred sixty-six million, seven hundred sixty-eight thousand, nine hundred seventy-eight".