1668526787261 has 4 divisors (see below), whose sum is σ = 1668532073724. Its totient is φ = 1668521500800.

The previous prime is 1668526787243. The next prime is 1668526787339. The reversal of 1668526787261 is 1627876258661.

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

It can be written as a sum of positive squares in 2 ways, for example, as 284962724761 + 1383564062500 = 533819^2 + 1176250^2 .

It is a cyclic number.

It is not a de Polignac number, because 1668526787261 - 2¹⁸ = 1668526525117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1668526787761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2137550 + ... + 2811791.

It is an arithmetic number, because the mean of its divisors is an integer number (417133018431).

Almost surely, 2^{1668526787261} is an apocalyptic number.

It is an amenable number.

1668526787261 is a deficient number, since it is larger than the sum of its proper divisors (5286463).

1668526787261 is an equidigital number, since it uses as much as digits as its factorization.

1668526787261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5286462.

The product of its digits is 81285120, while the sum is 65.

The spelling of 1668526787261 in words is "one trillion, six hundred sixty-eight billion, five hundred twenty-six million, seven hundred eighty-seven thousand, two hundred sixty-one".