491316077821 has 2 divisors, whose sum is σ = 491316077822. Its totient is φ = 491316077820.

The previous prime is 491316077797. The next prime is 491316077827. The reversal of 491316077821 is 128770613194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 285862384921 + 205453692900 = 534661^2 + 453270^2 .

It is a cyclic number.

It is not a de Polignac number, because 491316077821 - 2³⁵ = 456956339453 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491316077827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245658038910 + 245658038911.

It is an arithmetic number, because the mean of its divisors is an integer number (245658038911).

Almost surely, 2^491316077821 is an apocalyptic number.

It is an amenable number.

491316077821 is a deficient number, since it is larger than the sum of its proper divisors (1).

491316077821 is an equidigital number, since it uses as much as digits as its factorization.

491316077821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 508032, while the sum is 49.

The spelling of 491316077821 in words is "four hundred ninety-one billion, three hundred sixteen million, seventy-seven thousand, eight hundred twenty-one".