1821155478481 has 2 divisors, whose sum is σ = 1821155478482. Its totient is φ = 1821155478480.

The previous prime is 1821155478463. The next prime is 1821155478509. The reversal of 1821155478481 is 1848745511281.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 962782876225 + 858372602256 = 981215^2 + 926484^2 .

It is an emirp because it is prime and its reverse (1848745511281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1821155478481 - 2⁵ = 1821155478449 is a prime.

It is a super-2 number, since 2×1821155478481² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1821155478451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910577739240 + 910577739241.

It is an arithmetic number, because the mean of its divisors is an integer number (910577739241).

Almost surely, 2^{1821155478481} is an apocalyptic number.

It is an amenable number.

1821155478481 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821155478481 is an equidigital number, since it uses as much as digits as its factorization.

1821155478481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2867200, while the sum is 55.

The spelling of 1821155478481 in words is "one trillion, eight hundred twenty-one billion, one hundred fifty-five million, four hundred seventy-eight thousand, four hundred eighty-one".