99521 has 4 divisors (see below), whose sum is σ = 103872. Its totient is φ = 95172.

The previous prime is 99497. The next prime is 99523. The reversal of 99521 is 12599.

It is a happy number.

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: 12599 = 43 ⋅293.

It is a cyclic number.

It is not a de Polignac number, because 99521 - 2¹⁴ = 83137 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2141 + ... + 2186.

It is an arithmetic number, because the mean of its divisors is an integer number (25968).

2⁹⁹⁵²¹ is an apocalyptic number.

It is an amenable number.

99521 is a deficient number, since it is larger than the sum of its proper divisors (4351).

99521 is a wasteful number, since it uses less digits than its factorization.

99521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4350.

The product of its digits is 810, while the sum is 26.

The square root of 99521 is about 315.4694913934. The cubic root of 99521 is about 46.3416589884.

The spelling of 99521 in words is "ninety-nine thousand, five hundred twenty-one".