999145541981 has 2 divisors, whose sum is σ = 999145541982. Its totient is φ = 999145541980.

The previous prime is 999145541959. The next prime is 999145542023. The reversal of 999145541981 is 189145541999.

999145541981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 522678391225 + 476467150756 = 722965^2 + 690266^2 .

It is an emirp because it is prime and its reverse (189145541999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999145541981 - 2¹⁰ = 999145540957 is a prime.

It is a super-2 number, since 2×999145541981² (a number of 25 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999145546981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499572770990 + 499572770991.

It is an arithmetic number, because the mean of its divisors is an integer number (499572770991).

Almost surely, 2^999145541981 is an apocalyptic number.

It is an amenable number.

999145541981 is a deficient number, since it is larger than the sum of its proper divisors (1).

999145541981 is an equidigital number, since it uses as much as digits as its factorization.

999145541981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20995200, while the sum is 65.

The spelling of 999145541981 in words is "nine hundred ninety-nine billion, one hundred forty-five million, five hundred forty-one thousand, nine hundred eighty-one".