1814821997821 has 24 divisors (see below), whose sum is σ = 2179913544960. Its totient is φ = 1504903276800.

The previous prime is 1814821997753. The next prime is 1814821997893. The reversal of 1814821997821 is 1287991284181.

It is not a de Polignac number, because 1814821997821 - 2¹⁷ = 1814821866749 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1814821997821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1814821797821) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4625206 + ... + 5002216.

It is an arithmetic number, because the mean of its divisors is an integer number (90829731040).

Almost surely, 2^{1814821997821} is an apocalyptic number.

It is an amenable number.

1814821997821 is a deficient number, since it is larger than the sum of its proper divisors (365091547139).

1814821997821 is a wasteful number, since it uses less digits than its factorization.

1814821997821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 380225 (or 380218 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 61.

The spelling of 1814821997821 in words is "one trillion, eight hundred fourteen billion, eight hundred twenty-one million, nine hundred ninety-seven thousand, eight hundred twenty-one".