185556501881981 has 12 divisors (see below), whose sum is σ = 195838688506752. Its totient is φ = 175788531827784.

The previous prime is 185556501881977. The next prime is 185556501881999. The reversal of 185556501881981 is 189188105655581.

185556501881981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 185556501881981 - 2² = 185556501881977 is a prime.

It is a super-2 number, since 2×185556501881981² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (185556501881081) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32517716 + ... + 37795698.

It is an arithmetic number, because the mean of its divisors is an integer number (16319890708896).

Almost surely, 2^{185556501881981} is an apocalyptic number.

It is an amenable number.

185556501881981 is a deficient number, since it is larger than the sum of its proper divisors (10282186624771).

185556501881981 is an equidigital number, since it uses as much as digits as its factorization.

185556501881981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5375408 (or 5375389 counting only the distinct ones).

The product of its (nonzero) digits is 138240000, while the sum is 71.

The spelling of 185556501881981 in words is "one hundred eighty-five trillion, five hundred fifty-six billion, five hundred one million, eight hundred eighty-one thousand, nine hundred eighty-one".