491216521 has 2 divisors, whose sum is σ = 491216522. Its totient is φ = 491216520.

The previous prime is 491216507. The next prime is 491216611. The reversal of 491216521 is 125612194.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 489073225 + 2143296 = 22115^2 + 1464^2 .

It is a cyclic number.

It is not a de Polignac number, because 491216521 - 2¹³ = 491208329 is a prime.

It is not a weakly prime, because it can be changed into another prime (491216321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245608260 + 245608261.

It is an arithmetic number, because the mean of its divisors is an integer number (245608261).

Almost surely, 2^491216521 is an apocalyptic number.

It is an amenable number.

491216521 is a deficient number, since it is larger than the sum of its proper divisors (1).

491216521 is an equidigital number, since it uses as much as digits as its factorization.

491216521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 491216521 is about 22163.4049956229. The cubic root of 491216521 is about 789.0254076955.

The spelling of 491216521 in words is "four hundred ninety-one million, two hundred sixteen thousand, five hundred twenty-one".