1998000509 has 2 divisors, whose sum is σ = 1998000510. Its totient is φ = 1998000508.

The previous prime is 1998000493. The next prime is 1998000523. The reversal of 1998000509 is 9050008991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1009841284 + 988159225 = 31778^2 + 31435^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998000509 - 2⁴ = 1998000493 is a prime.

It is a super-4 number, since 4×1998000509⁴ (a number of 38 digits) contains 4444 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998000209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999000254 + 999000255.

It is an arithmetic number, because the mean of its divisors is an integer number (999000255).

Almost surely, 2^1998000509 is an apocalyptic number.

It is an amenable number.

1998000509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998000509 is an equidigital number, since it uses as much as digits as its factorization.

1998000509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29160, while the sum is 41.

The square root of 1998000509 is about 44698.9989708942. The cubic root of 1998000509 is about 1259.5010430971.

The spelling of 1998000509 in words is "one billion, nine hundred ninety-eight million, five hundred nine", and thus it is an aban number.