491861993 has 16 divisors (see below), whose sum is σ = 580331136. Its totient is φ = 408119040.

The previous prime is 491861897. The next prime is 491862013. The reversal of 491861993 is 399168194.

It is not a de Polignac number, because 491861993 - 2²⁰ = 490813417 is a prime.

It is not an unprimeable number, because it can be changed into a prime (491861393) by changing a digit.

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, 26783 + ... + 41243.

It is an arithmetic number, because the mean of its divisors is an integer number (36270696).

Almost surely, 2^491861993 is an apocalyptic number.

491861993 is a gapful number since it is divisible by the number (43) formed by its first and last digit.

It is an amenable number.

491861993 is a deficient number, since it is larger than the sum of its proper divisors (88469143).

491861993 is a wasteful number, since it uses less digits than its factorization.

491861993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14624.

The product of its digits is 419904, while the sum is 50.

The square root of 491861993 is about 22177.9618766017. The cubic root of 491861993 is about 789.3708567819.

The spelling of 491861993 in words is "four hundred ninety-one million, eight hundred sixty-one thousand, nine hundred ninety-three".