99724921 has 2 divisors, whose sum is σ = 99724922. Its totient is φ = 99724920.

The previous prime is 99724913. The next prime is 99724943. The reversal of 99724921 is 12942799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59845696 + 39879225 = 7736^2 + 6315^2 .

It is an emirp because it is prime and its reverse (12942799) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 99724921 - 2³ = 99724913 is a prime.

It is not a weakly prime, because it can be changed into another prime (99724951) 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, 49862460 + 49862461.

It is an arithmetic number, because the mean of its divisors is an integer number (49862461).

Almost surely, 2^99724921 is an apocalyptic number.

It is an amenable number.

99724921 is a deficient number, since it is larger than the sum of its proper divisors (1).

99724921 is an equidigital number, since it uses as much as digits as its factorization.

99724921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 43.

The square root of 99724921 is about 9986.2365784113. The cubic root of 99724921 is about 463.7328913124.

The spelling of 99724921 in words is "ninety-nine million, seven hundred twenty-four thousand, nine hundred twenty-one".