1998409609 has 4 divisors (see below), whose sum is σ = 2283896704. Its totient is φ = 1712922516.

The previous prime is 1998409571. The next prime is 1998409639. The reversal of 1998409609 is 9069048991.

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.

It is a cyclic number.

It is not a de Polignac number, because 1998409609 - 2⁷ = 1998409481 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1998409609.

It is not an unprimeable number, because it can be changed into a prime (1998409639) 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, 142743537 + ... + 142743550.

It is an arithmetic number, because the mean of its divisors is an integer number (570974176).

Almost surely, 2^1998409609 is an apocalyptic number.

It is an amenable number.

1998409609 is a deficient number, since it is larger than the sum of its proper divisors (285487095).

1998409609 is an equidigital number, since it uses as much as digits as its factorization.

1998409609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285487094.

The product of its (nonzero) digits is 1259712, while the sum is 55.

The square root of 1998409609 is about 44703.5749017906. The cubic root of 1998409609 is about 1259.5870001512.

The spelling of 1998409609 in words is "one billion, nine hundred ninety-eight million, four hundred nine thousand, six hundred nine".