1666666819851 has 16 divisors (see below), whose sum is σ = 2424334969728. Its totient is φ = 1010062635200.

The previous prime is 1666666819819. The next prime is 1666666819877. The reversal of 1666666819851 is 1589186666661.

It is a cyclic number.

It is not a de Polignac number, because 1666666819851 - 2⁵ = 1666666819819 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666666819451) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69690 + ... + 1827071.

It is an arithmetic number, because the mean of its divisors is an integer number (151520935608).

Almost surely, 2^{1666666819851} is an apocalyptic number.

1666666819851 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1666666819851 is a deficient number, since it is larger than the sum of its proper divisors (757668149877).

1666666819851 is a wasteful number, since it uses less digits than its factorization.

1666666819851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923402.

The product of its digits is 134369280, while the sum is 69.

The spelling of 1666666819851 in words is "one trillion, six hundred sixty-six billion, six hundred sixty-six million, eight hundred nineteen thousand, eight hundred fifty-one".