999521 has 2 divisors, whose sum is σ = 999522. Its totient is φ = 999520.

The previous prime is 999499. The next prime is 999529. The reversal of 999521 is 125999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 929296 + 70225 = 964^2 + 265^2 .

It is a cyclic number.

It is not a de Polignac number, because 999521 - 2¹⁰ = 998497 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a nialpdrome in base 10.

It is not a weakly prime, because it can be changed into another prime (999529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499760 + 499761.

It is an arithmetic number, because the mean of its divisors is an integer number (499761).

2⁹⁹⁹⁵²¹ is an apocalyptic number.

It is an amenable number.

999521 is a deficient number, since it is larger than the sum of its proper divisors (1).

999521 is an equidigital number, since it uses as much as digits as its factorization.

999521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7290, while the sum is 35.

The square root of 999521 is about 999.7604713130. The cubic root of 999521 is about 99.9840307833.

The spelling of 999521 in words is "nine hundred ninety-nine thousand, five hundred twenty-one".