1998520805 has 8 divisors (see below), whose sum is σ = 2399911800. Its totient is φ = 1597692096.

The previous prime is 1998520789. The next prime is 1998520829. The reversal of 1998520805 is 5080258991.

It can be written as a sum of positive squares in 4 ways, for example, as 165225316 + 1833295489 = 12854^2 + 42817^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1998520805 - 2⁴ = 1998520789 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1998520805.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 132710 + ... + 146999.

It is an arithmetic number, because the mean of its divisors is an integer number (299988975).

Almost surely, 2^1998520805 is an apocalyptic number.

It is an amenable number.

1998520805 is a deficient number, since it is larger than the sum of its proper divisors (401390995).

1998520805 is a wasteful number, since it uses less digits than its factorization.

1998520805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281143.

The product of its (nonzero) digits is 259200, while the sum is 47.

The square root of 1998520805 is about 44704.8185881567. The cubic root of 1998520805 is about 1259.6103618013.

The spelling of 1998520805 in words is "one billion, nine hundred ninety-eight million, five hundred twenty thousand, eight hundred five".