9861811681 has 4 divisors (see below), whose sum is σ = 9885924100. Its totient is φ = 9837699264.

The previous prime is 9861811669. The next prime is 9861811693. The reversal of 9861811681 is 1861181689.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (9861811669) and next prime (9861811693).

It can be written as a sum of positive squares in 2 ways, for example, as 3671269281 + 6190542400 = 60591^2 + 78680^2 .

It is a cyclic number.

It is not a de Polignac number, because 9861811681 - 2⁵ = 9861811649 is a prime.

It is a super-2 number, since 2×9861811681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9861815681) 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 in 3 ways as a sum of consecutive naturals, for example, 12055596 + ... + 12056413.

It is an arithmetic number, because the mean of its divisors is an integer number (2471481025).

Almost surely, 2^9861811681 is an apocalyptic number.

It is an amenable number.

9861811681 is a deficient number, since it is larger than the sum of its proper divisors (24112419).

9861811681 is a wasteful number, since it uses less digits than its factorization.

9861811681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24112418.

The product of its digits is 165888, while the sum is 49.

The square root of 9861811681 is about 99306.6547669390. The cubic root of 9861811681 is about 2144.4646998751.

The spelling of 9861811681 in words is "nine billion, eight hundred sixty-one million, eight hundred eleven thousand, six hundred eighty-one".