491942781 has 32 divisors (see below), whose sum is σ = 797005440. Its totient is φ = 297417600.

The previous prime is 491942771. The next prime is 491942797. The reversal of 491942781 is 187249194.

It is a happy number.

491942781 is a `hidden beast` number, since 491 + 94 + 2 + 78 + 1 = 666.

It is not a de Polignac number, because 491942781 - 2¹⁰ = 491941757 is a prime.

It is a super-2 number, since 2×491942781² = 484015399556027922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491942771) 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, 135121 + ... + 138713.

It is an arithmetic number, because the mean of its divisors is an integer number (24906420).

Almost surely, 2^491942781 is an apocalyptic number.

It is an amenable number.

491942781 is a deficient number, since it is larger than the sum of its proper divisors (305062659).

491942781 is a wasteful number, since it uses less digits than its factorization.

491942781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4074 (or 4068 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 491942781 is about 22179.7831594450. The cubic root of 491942781 is about 789.4140722926.

The spelling of 491942781 in words is "four hundred ninety-one million, nine hundred forty-two thousand, seven hundred eighty-one".