2005206115661 has 12 divisors (see below), whose sum is σ = 2332629115740. Its totient is φ = 1718716849920.

The previous prime is 2005206115643. The next prime is 2005206115663. The reversal of 2005206115661 is 1665116025002.

It can be written as a sum of positive squares in 2 ways, for example, as 1206524299561 + 798681816100 = 1098419^2 + 893690^2 .

It is not a de Polignac number, because 2005206115661 - 2³⁸ = 1730328208717 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2005206115663) 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 11 ways as a sum of consecutive naturals, for example, 2588531 + ... + 3272751.

It is an arithmetic number, because the mean of its divisors is an integer number (194385759645).

Almost surely, 2^{2005206115661} is an apocalyptic number.

It is an amenable number.

2005206115661 is a deficient number, since it is larger than the sum of its proper divisors (327423000079).

2005206115661 is an equidigital number, since it uses as much as digits as its factorization.

2005206115661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 744044 (or 744037 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 35.

The spelling of 2005206115661 in words is "two trillion, five billion, two hundred six million, one hundred fifteen thousand, six hundred sixty-one".