99911821 has 2 divisors, whose sum is σ = 99911822. Its totient is φ = 99911820.

The previous prime is 99911813. The next prime is 99911827. The reversal of 99911821 is 12811999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54834025 + 45077796 = 7405^2 + 6714^2 .

It is a cyclic number.

It is not a de Polignac number, because 99911821 - 2³ = 99911813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99911827) 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, 49955910 + 49955911.

It is an arithmetic number, because the mean of its divisors is an integer number (49955911).

Almost surely, 2^99911821 is an apocalyptic number.

It is an amenable number.

99911821 is a deficient number, since it is larger than the sum of its proper divisors (1).

99911821 is an equidigital number, since it uses as much as digits as its factorization.

99911821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 40.

The square root of 99911821 is about 9995.5900776292. The cubic root of 99911821 is about 464.0224130201.

The spelling of 99911821 in words is "ninety-nine million, nine hundred eleven thousand, eight hundred twenty-one".