9899779961 has 2 divisors, whose sum is σ = 9899779962. Its totient is φ = 9899779960.

The previous prime is 9899779957. The next prime is 9899780003. The reversal of 9899779961 is 1699779989.

9899779961 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., 5627850361 + 4271929600 = 75019^2 + 65360^2 .

It is a cyclic number.

It is not a de Polignac number, because 9899779961 - 2² = 9899779957 is a prime.

It is not a weakly prime, because it can be changed into another prime (9899770961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4949889980 + 4949889981.

It is an arithmetic number, because the mean of its divisors is an integer number (4949889981).

Almost surely, 2^9899779961 is an apocalyptic number.

It is an amenable number.

9899779961 is a deficient number, since it is larger than the sum of its proper divisors (1).

9899779961 is an equidigital number, since it uses as much as digits as its factorization.

9899779961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 138883248, while the sum is 74.

The square root of 9899779961 is about 99497.6379669387. The cubic root of 9899779961 is about 2147.2132606802.

The spelling of 9899779961 in words is "nine billion, eight hundred ninety-nine million, seven hundred seventy-nine thousand, nine hundred sixty-one".