1998681905 has 16 divisors (see below), whose sum is σ = 2619316224. Its totient is φ = 1451998080.

The previous prime is 1998681871. The next prime is 1998681917. The reversal of 1998681905 is 5091868991.

It is not a de Polignac number, because 1998681905 - 2¹⁰ = 1998680881 is a prime.

It is a Duffinian 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 15 ways as a sum of consecutive naturals, for example, 32144 + ... + 70926.

It is an arithmetic number, because the mean of its divisors is an integer number (163707264).

Almost surely, 2^1998681905 is an apocalyptic number.

It is an amenable number.

1998681905 is a deficient number, since it is larger than the sum of its proper divisors (620634319).

1998681905 is a wasteful number, since it uses less digits than its factorization.

1998681905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39736.

The product of its (nonzero) digits is 1399680, while the sum is 56.

The square root of 1998681905 is about 44706.6203710368. The cubic root of 1998681905 is about 1259.6442064623.

The spelling of 1998681905 in words is "one billion, nine hundred ninety-eight million, six hundred eighty-one thousand, nine hundred five".