999999000521 has 2 divisors, whose sum is σ = 999999000522. Its totient is φ = 999999000520.

The previous prime is 999999000509. The next prime is 999999000547. The reversal of 999999000521 is 125000999999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 996075857296 + 3923143225 = 998036^2 + 62635^2 .

It is an emirp because it is prime and its reverse (125000999999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999999000521 - 2¹⁸ = 999998738377 is a prime.

It is not a weakly prime, because it can be changed into another prime (999999000551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499999500260 + 499999500261.

It is an arithmetic number, because the mean of its divisors is an integer number (499999500261).

Almost surely, 2^999999000521 is an apocalyptic number.

It is an amenable number.

999999000521 is a deficient number, since it is larger than the sum of its proper divisors (1).

999999000521 is an equidigital number, since it uses as much as digits as its factorization.

999999000521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5314410, while the sum is 62.

The spelling of 999999000521 in words is "nine hundred ninety-nine billion, nine hundred ninety-nine million, five hundred twenty-one", and thus it is an aban number.