99880021 has 2 divisors, whose sum is σ = 99880022. Its totient is φ = 99880020.

The previous prime is 99880019. The next prime is 99880051. The reversal of 99880021 is 12008899.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94187025 + 5692996 = 9705^2 + 2386^2 .

It is a cyclic number.

It is not a de Polignac number, because 99880021 - 2¹ = 99880019 is a prime.

Together with 99880019, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99880051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49940010 + 49940011.

It is an arithmetic number, because the mean of its divisors is an integer number (49940011).

Almost surely, 2^99880021 is an apocalyptic number.

It is an amenable number.

99880021 is a deficient number, since it is larger than the sum of its proper divisors (1).

99880021 is an equidigital number, since it uses as much as digits as its factorization.

99880021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 37.

The square root of 99880021 is about 9993.9992495497. Note that the first 3 decimals coincide. The cubic root of 99880021 is about 463.9731780101.

The spelling of 99880021 in words is "ninety-nine million, eight hundred eighty thousand, twenty-one".