1666185480649 has 4 divisors (see below), whose sum is σ = 1666189392336. Its totient is φ = 1666181568964.

The previous prime is 1666185480613. The next prime is 1666185480667. The reversal of 1666185480649 is 9460845816661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1666185480649 - 2¹⁵ = 1666185447881 is a prime.

It is a super-2 number, since 2×1666185480649² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666185480049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1226179 + ... + 2199064.

It is an arithmetic number, because the mean of its divisors is an integer number (416547348084).

Almost surely, 2^{1666185480649} is an apocalyptic number.

It is an amenable number.

1666185480649 is a deficient number, since it is larger than the sum of its proper divisors (3911687).

1666185480649 is an equidigital number, since it uses as much as digits as its factorization.

1666185480649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3911686.

The product of its (nonzero) digits is 59719680, while the sum is 64.

The spelling of 1666185480649 in words is "one trillion, six hundred sixty-six billion, one hundred eighty-five million, four hundred eighty thousand, six hundred forty-nine".