20987001181 has 2 divisors, whose sum is σ = 20987001182. Its totient is φ = 20987001180.

The previous prime is 20987001173. The next prime is 20987001187. The reversal of 20987001181 is 18110078902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20890077156 + 96924025 = 144534^2 + 9845^2 .

It is a cyclic number.

It is not a de Polignac number, because 20987001181 - 2³ = 20987001173 is a prime.

It is a super-2 number, since 2×20987001181² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20987001181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20987001187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493500590 + 10493500591.

It is an arithmetic number, because the mean of its divisors is an integer number (10493500591).

Almost surely, 2^20987001181 is an apocalyptic number.

It is an amenable number.

20987001181 is a deficient number, since it is larger than the sum of its proper divisors (1).

20987001181 is an equidigital number, since it uses as much as digits as its factorization.

20987001181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8064, while the sum is 37.

The spelling of 20987001181 in words is "twenty billion, nine hundred eighty-seven million, one thousand, one hundred eighty-one".