1666751016691 has 8 divisors (see below), whose sum is σ = 1672168189104. Its totient is φ = 1661336144160.

The previous prime is 1666751016647. The next prime is 1666751016709. The reversal of 1666751016691 is 1966101576661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1666751016691 - 2¹⁷ = 1666750885619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666751016641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 882801 + ... + 2028013.

It is an arithmetic number, because the mean of its divisors is an integer number (209021023638).

Almost surely, 2^{1666751016691} is an apocalyptic number.

1666751016691 is a deficient number, since it is larger than the sum of its proper divisors (5417172413).

1666751016691 is a wasteful number, since it uses less digits than its factorization.

1666751016691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1149941.

The product of its (nonzero) digits is 2449440, while the sum is 55.

The spelling of 1666751016691 in words is "one trillion, six hundred sixty-six billion, seven hundred fifty-one million, sixteen thousand, six hundred ninety-one".