2106166662661 has 4 divisors (see below), whose sum is σ = 2106230170924. Its totient is φ = 2106103154400.

The previous prime is 2106166662637. The next prime is 2106166662779. The reversal of 2106166662661 is 1662666616012.

It is a happy number.

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 1711884392100 + 394282270561 = 1308390^2 + 627919^2 .

It is a cyclic number.

It is not a de Polignac number, because 2106166662661 - 2⁵ = 2106166662629 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 (2106166662631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31704360 + ... + 31770721.

It is an arithmetic number, because the mean of its divisors is an integer number (526557542731).

Almost surely, 2^{2106166662661} is an apocalyptic number.

It is an amenable number.

2106166662661 is a deficient number, since it is larger than the sum of its proper divisors (63508263).

2106166662661 is an equidigital number, since it uses as much as digits as its factorization.

2106166662661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63508262.

The product of its (nonzero) digits is 1119744, while the sum is 49.

The spelling of 2106166662661 in words is "two trillion, one hundred six billion, one hundred sixty-six million, six hundred sixty-two thousand, six hundred sixty-one".