1665000061861 has 2 divisors, whose sum is σ = 1665000061862. Its totient is φ = 1665000061860.

The previous prime is 1665000061849. The next prime is 1665000061877. The reversal of 1665000061861 is 1681600005661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1655774459361 + 9225602500 = 1286769^2 + 96050^2 .

It is a cyclic number.

It is not a de Polignac number, because 1665000061861 - 2¹³ = 1665000053669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1665000061891) 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 as a sum of consecutive naturals, namely, 832500030930 + 832500030931.

It is an arithmetic number, because the mean of its divisors is an integer number (832500030931).

Almost surely, 2^{1665000061861} is an apocalyptic number.

It is an amenable number.

1665000061861 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665000061861 is an equidigital number, since it uses as much as digits as its factorization.

1665000061861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 40.

The spelling of 1665000061861 in words is "one trillion, six hundred sixty-five billion, sixty-one thousand, eight hundred sixty-one".