1666666666651 has 4 divisors (see below), whose sum is σ = 1904761904752. Its totient is φ = 1428571428552.

The previous prime is 1666666666573. The next prime is 1666666666657. The reversal of 1666666666651 is 1566666666661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1666666666651 - 2³⁷ = 1529227713179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1666666666657) 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 3 ways as a sum of consecutive naturals, for example, 119047619040 + ... + 119047619053.

It is an arithmetic number, because the mean of its divisors is an integer number (476190476188).

Almost surely, 2^{1666666666651} is an apocalyptic number.

1666666666651 is a deficient number, since it is larger than the sum of its proper divisors (238095238101).

1666666666651 is an equidigital number, since it uses as much as digits as its factorization.

1666666666651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238095238100.

The product of its digits is 302330880, while the sum is 67.

The spelling of 1666666666651 in words is "one trillion, six hundred sixty-six billion, six hundred sixty-six million, six hundred sixty-six thousand, six hundred fifty-one".