9985555861 has 2 divisors, whose sum is σ = 9985555862. Its totient is φ = 9985555860.

The previous prime is 9985555837. The next prime is 9985555883. The reversal of 9985555861 is 1685555899.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9798030225 + 187525636 = 98985^2 + 13694^2 .

It is a cyclic number.

It is not a de Polignac number, because 9985555861 - 2⁷ = 9985555733 is a prime.

It is a super-2 number, since 2×9985555861² (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 9985555861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9985555661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4992777930 + 4992777931.

It is an arithmetic number, because the mean of its divisors is an integer number (4992777931).

Almost surely, 2^9985555861 is an apocalyptic number.

It is an amenable number.

9985555861 is a deficient number, since it is larger than the sum of its proper divisors (1).

9985555861 is an equidigital number, since it uses as much as digits as its factorization.

9985555861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19440000, while the sum is 61.

The square root of 9985555861 is about 99927.7532070045. The cubic root of 9985555861 is about 2153.3968917303.

The spelling of 9985555861 in words is "nine billion, nine hundred eighty-five million, five hundred fifty-five thousand, eight hundred sixty-one".