5509550815981 has 2 divisors, whose sum is σ = 5509550815982. Its totient is φ = 5509550815980.

The previous prime is 5509550815943. The next prime is 5509550816087. The reversal of 5509550815981 is 1895180559055.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5143597202500 + 365953613481 = 2267950^2 + 604941^2 .

It is a cyclic number.

It is not a de Polignac number, because 5509550815981 - 2²³ = 5509542427373 is a prime.

It is a super-2 number, since 2×5509550815981² (a number of 26 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (5509550815931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2754775407990 + 2754775407991.

It is an arithmetic number, because the mean of its divisors is an integer number (2754775407991).

Almost surely, 2^{5509550815981} is an apocalyptic number.

It is an amenable number.

5509550815981 is a deficient number, since it is larger than the sum of its proper divisors (1).

5509550815981 is an equidigital number, since it uses as much as digits as its factorization.

5509550815981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200000, while the sum is 61.

The spelling of 5509550815981 in words is "five trillion, five hundred nine billion, five hundred fifty million, eight hundred fifteen thousand, nine hundred eighty-one".