1991409205 has 8 divisors (see below), whose sum is σ = 2390787072. Its totient is φ = 1592396688.

The previous prime is 1991409197. The next prime is 1991409229. The reversal of 1991409205 is 5029041991.

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 1991409205 - 2³ = 1991409197 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79197 + ... + 101266.

It is an arithmetic number, because the mean of its divisors is an integer number (298848384).

Almost surely, 2^1991409205 is an apocalyptic number.

It is an amenable number.

1991409205 is a deficient number, since it is larger than the sum of its proper divisors (399377867).

1991409205 is a wasteful number, since it uses less digits than its factorization.

1991409205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182675.

The product of its (nonzero) digits is 29160, while the sum is 40.

The square root of 1991409205 is about 44625.2081787861. The cubic root of 1991409205 is about 1258.1145069045.

The spelling of 1991409205 in words is "one billion, nine hundred ninety-one million, four hundred nine thousand, two hundred five".