1821491811641 has 4 divisors (see below), whose sum is σ = 1827311274612. Its totient is φ = 1815672348672.

The previous prime is 1821491811631. The next prime is 1821491811701. The reversal of 1821491811641 is 1461181941281.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 82532671225 + 1738959140416 = 287285^2 + 1318696^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821491811641 - 2¹⁰ = 1821491810617 is a prime.

It is a super-2 number, since 2×1821491811641² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1821491811631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2909731016 + ... + 2909731641.

It is an arithmetic number, because the mean of its divisors is an integer number (456827818653).

Almost surely, 2^{1821491811641} is an apocalyptic number.

It is an amenable number.

1821491811641 is a deficient number, since it is larger than the sum of its proper divisors (5819462971).

1821491811641 is an equidigital number, since it uses as much as digits as its factorization.

1821491811641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5819462970.

The product of its digits is 110592, while the sum is 47.

The spelling of 1821491811641 in words is "one trillion, eight hundred twenty-one billion, four hundred ninety-one million, eight hundred eleven thousand, six hundred forty-one".