491639856 has 80 divisors (see below), whose sum is σ = 1311666048. Its totient is φ = 158579200.

The previous prime is 491639851. The next prime is 491639857. The reversal of 491639856 is 658936194.

It is a junction number, because it is equal to n+sod(n) for n = 491639799 and 491639808.

It is not an unprimeable number, because it can be changed into a prime (491639851) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 256855 + ... + 258761.

Almost surely, 2^491639856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 491639856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (655833024).

491639856 is an abundant number, since it is smaller than the sum of its proper divisors (820026192).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

491639856 is a wasteful number, since it uses less digits than its factorization.

491639856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2090 (or 2084 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 51.

The square root of 491639856 is about 22172.9532539082. The cubic root of 491639856 is about 789.2520057760.

The spelling of 491639856 in words is "four hundred ninety-one million, six hundred thirty-nine thousand, eight hundred fifty-six".