99999521 has 4 divisors (see below), whose sum is σ = 103225344. Its totient is φ = 96773700.

The previous prime is 99999517. The next prime is 99999539. The reversal of 99999521 is 12599999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12599999 = 107 ⋅117757.

It is a cyclic number.

It is not a de Polignac number, because 99999521 - 2² = 99999517 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99999541) 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 in 3 ways as a sum of consecutive naturals, for example, 1612865 + ... + 1612926.

It is an arithmetic number, because the mean of its divisors is an integer number (25806336).

Almost surely, 2^99999521 is an apocalyptic number.

It is an amenable number.

99999521 is a deficient number, since it is larger than the sum of its proper divisors (3225823).

99999521 is a wasteful number, since it uses less digits than its factorization.

99999521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3225822.

The product of its digits is 590490, while the sum is 53.

The square root of 99999521 is about 9999.9760499713. The cubic root of 99999521 is about 464.1581422531.

The spelling of 99999521 in words is "ninety-nine million, nine hundred ninety-nine thousand, five hundred twenty-one".