2006556651661 has 4 divisors (see below), whose sum is σ = 2034818013024. Its totient is φ = 1978295290300.

The previous prime is 2006556651653. The next prime is 2006556651667. The reversal of 2006556651661 is 1661566556002.

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 2006556651661 - 2³ = 2006556651653 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2006556651667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14130680575 + ... + 14130680716.

It is an arithmetic number, because the mean of its divisors is an integer number (508704503256).

Almost surely, 2^{2006556651661} is an apocalyptic number.

It is an amenable number.

2006556651661 is a deficient number, since it is larger than the sum of its proper divisors (28261361363).

2006556651661 is an equidigital number, since it uses as much as digits as its factorization.

2006556651661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28261361362.

The product of its (nonzero) digits is 1944000, while the sum is 49.

The spelling of 2006556651661 in words is "two trillion, six billion, five hundred fifty-six million, six hundred fifty-one thousand, six hundred sixty-one".