5551550111561 has 2 divisors, whose sum is σ = 5551550111562. Its totient is φ = 5551550111560.

The previous prime is 5551550111531. The next prime is 5551550111663. The reversal of 5551550111561 is 1651110551555.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5427315715600 + 124234395961 = 2329660^2 + 352469^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-5551550111561 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (5551550111531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2775775055780 + 2775775055781.

It is an arithmetic number, because the mean of its divisors is an integer number (2775775055781).

Almost surely, 2^{5551550111561} is an apocalyptic number.

It is an amenable number.

5551550111561 is a deficient number, since it is larger than the sum of its proper divisors (1).

5551550111561 is an equidigital number, since it uses as much as digits as its factorization.

5551550111561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93750, while the sum is 41.

The spelling of 5551550111561 in words is "five trillion, five hundred fifty-one billion, five hundred fifty million, one hundred eleven thousand, five hundred sixty-one".