491639904 has 216 divisors, whose sum is σ = 1673944272. Its totient is φ = 134069760.

The previous prime is 491639893. The next prime is 491639963. The reversal of 491639904 is 409936194.

491639904 is a `hidden beast` number, since 4 + 9 + 1 + 639 + 9 + 0 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 491639904.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1066234 + ... + 1066694.

It is an arithmetic number, because the mean of its divisors is an integer number (7749742).

Almost surely, 2^491639904 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 491639904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (836972136).

491639904 is an abundant number, since it is smaller than the sum of its proper divisors (1182304368).

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

491639904 is a wasteful number, since it uses less digits than its factorization.

491639904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530 (or 496 counting only the distinct ones).

The product of its (nonzero) digits is 209952, while the sum is 45.

The square root of 491639904 is about 22172.9543363080. The cubic root of 491639904 is about 789.2520314616.

The spelling of 491639904 in words is "four hundred ninety-one million, six hundred thirty-nine thousand, nine hundred four".