99899981 has 2 divisors, whose sum is σ = 99899982. Its totient is φ = 99899980.

The previous prime is 99899959. The next prime is 99899999. The reversal of 99899981 is 18999899.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72505225 + 27394756 = 8515^2 + 5234^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-99899981 is a prime.

It is a super-2 number, since 2×99899981² = 19960012407600722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99899951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49949990 + 49949991.

It is an arithmetic number, because the mean of its divisors is an integer number (49949991).

Almost surely, 2^99899981 is an apocalyptic number.

It is an amenable number.

99899981 is a deficient number, since it is larger than the sum of its proper divisors (1).

99899981 is an equidigital number, since it uses as much as digits as its factorization.

99899981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3779136, while the sum is 62.

The square root of 99899981 is about 9994.9977988992. The cubic root of 99899981 is about 464.0040827153.

The spelling of 99899981 in words is "ninety-nine million, eight hundred ninety-nine thousand, nine hundred eighty-one".