491164090561 has 3 divisors (see below), whose sum is σ = 491164791393. Its totient is φ = 491163389730.

The previous prime is 491164090499. The next prime is 491164090579. The reversal of 491164090561 is 165090461194.

The square root of 491164090561 is 700831.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 491164090561 - 2¹⁵ = 491164057793 is a prime.

It is a super-2 number, since 2×491164090561² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491164099561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 350416 + ... + 1051246.

It is an arithmetic number, because the mean of its divisors is an integer number (163721597131).

Almost surely, 2^491164090561 is an apocalyptic number.

491164090561 is the 700831-st square number.

491164090561 is the 350416-th centered octagonal number.

It is an amenable number.

491164090561 is a deficient number, since it is larger than the sum of its proper divisors (700832).

491164090561 is an frugal number, since it uses more digits than its factorization.

491164090561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1401662 (or 700831 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 46.

The spelling of 491164090561 in words is "four hundred ninety-one billion, one hundred sixty-four million, ninety thousand, five hundred sixty-one".