491712561 has 24 divisors (see below), whose sum is σ = 746830656. Its totient is φ = 311145120.

The previous prime is 491712517. The next prime is 491712563. The reversal of 491712561 is 165217194.

491712561 is a `hidden beast` number, since 4 + 91 + 7 + 1 + 2 + 561 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-491712561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (491712563) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18051 + ... + 36183.

It is an arithmetic number, because the mean of its divisors is an integer number (31117944).

Almost surely, 2^491712561 is an apocalyptic number.

It is an amenable number.

491712561 is a deficient number, since it is larger than the sum of its proper divisors (255118095).

491712561 is a wasteful number, since it uses less digits than its factorization.

491712561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18293 (or 18290 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 491712561 is about 22174.5926907350. The cubic root of 491712561 is about 789.2909094152.

The spelling of 491712561 in words is "four hundred ninety-one million, seven hundred twelve thousand, five hundred sixty-one".