842489786821 has 2 divisors, whose sum is σ = 842489786822. Its totient is φ = 842489786820.

The previous prime is 842489786783. The next prime is 842489786899. The reversal of 842489786821 is 128687984248.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 573595684321 + 268894102500 = 757361^2 + 518550^2 .

It is a cyclic number.

It is not a de Polignac number, because 842489786821 - 2⁷ = 842489786693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (842489786221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 421244893410 + 421244893411.

It is an arithmetic number, because the mean of its divisors is an integer number (421244893411).

Almost surely, 2^842489786821 is an apocalyptic number.

It is an amenable number.

842489786821 is a deficient number, since it is larger than the sum of its proper divisors (1).

842489786821 is an equidigital number, since it uses as much as digits as its factorization.

842489786821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 99090432, while the sum is 67.

The spelling of 842489786821 in words is "eight hundred forty-two billion, four hundred eighty-nine million, seven hundred eighty-six thousand, eight hundred twenty-one".