491991819 has 8 divisors (see below), whose sum is σ = 715624512. Its totient is φ = 298176840.

The previous prime is 491991803. The next prime is 491991823. The reversal of 491991819 is 918199194.

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

It is not a de Polignac number, because 491991819 - 2⁴ = 491991803 is a prime.

It is a super-2 number, since 2×491991819² = 484111899925857522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (491991859) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7454389 + ... + 7454454.

It is an arithmetic number, because the mean of its divisors is an integer number (89453064).

Almost surely, 2^491991819 is an apocalyptic number.

491991819 is a deficient number, since it is larger than the sum of its proper divisors (223632693).

491991819 is a wasteful number, since it uses less digits than its factorization.

491991819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14908857.

The product of its digits is 209952, while the sum is 51.

The square root of 491991819 is about 22180.8885980702. Note that the first 3 decimals coincide. The cubic root of 491991819 is about 789.4403016310.

The spelling of 491991819 in words is "four hundred ninety-one million, nine hundred ninety-one thousand, eight hundred nineteen".