9909999881 has 2 divisors, whose sum is σ = 9909999882. Its totient is φ = 9909999880.

The previous prime is 9909999877. The next prime is 9909999889. The reversal of 9909999881 is 1889999099.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9222721225 + 687278656 = 96035^2 + 26216^2 .

It is a cyclic number.

It is not a de Polignac number, because 9909999881 - 2² = 9909999877 is a prime.

It is a super-2 number, since 2×9909999881² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (9909999889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4954999940 + 4954999941.

It is an arithmetic number, because the mean of its divisors is an integer number (4954999941).

Almost surely, 2^9909999881 is an apocalyptic number.

It is an amenable number.

9909999881 is a deficient number, since it is larger than the sum of its proper divisors (1).

9909999881 is an equidigital number, since it uses as much as digits as its factorization.

9909999881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34012224, while the sum is 71.

The square root of 9909999881 is about 99548.9823202628. The cubic root of 9909999881 is about 2147.9518899169.

The spelling of 9909999881 in words is "nine billion, nine hundred nine million, nine hundred ninety-nine thousand, eight hundred eighty-one".