2111551056661 has 4 divisors (see below), whose sum is σ = 2160656895232. Its totient is φ = 2062445218092.

The previous prime is 2111551056623. The next prime is 2111551056677. The reversal of 2111551056661 is 1666501551112.

It is a happy number.

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 2111551056661 - 2⁷ = 2111551056533 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 (2111551056161) 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, 24552919221 + ... + 24552919306.

It is an arithmetic number, because the mean of its divisors is an integer number (540164223808).

Almost surely, 2^{2111551056661} is an apocalyptic number.

It is an amenable number.

2111551056661 is a deficient number, since it is larger than the sum of its proper divisors (49105838571).

2111551056661 is an equidigital number, since it uses as much as digits as its factorization.

2111551056661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49105838570.

The product of its (nonzero) digits is 54000, while the sum is 40.

The spelling of 2111551056661 in words is "two trillion, one hundred eleven billion, five hundred fifty-one million, fifty-six thousand, six hundred sixty-one".