991940205 has 32 divisors (see below), whose sum is σ = 1658087424. Its totient is φ = 505429056.

The previous prime is 991940197. The next prime is 991940207. The reversal of 991940205 is 502049199.

It is not a de Polignac number, because 991940205 - 2³ = 991940197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991940207) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 498222 + ... + 500208.

It is an arithmetic number, because the mean of its divisors is an integer number (51815232).

Almost surely, 2^991940205 is an apocalyptic number.

It is an amenable number.

991940205 is a deficient number, since it is larger than the sum of its proper divisors (666147219).

991940205 is a wasteful number, since it uses less digits than its factorization.

991940205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3465.

The product of its (nonzero) digits is 29160, while the sum is 39.

The square root of 991940205 is about 31495.0822351681. The cubic root of 991940205 is about 997.3061513624.

The spelling of 991940205 in words is "nine hundred ninety-one million, nine hundred forty thousand, two hundred five".