1812811421 has 2 divisors, whose sum is σ = 1812811422. Its totient is φ = 1812811420.

The previous prime is 1812811391. The next prime is 1812811423. The reversal of 1812811421 is 1241182181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1665456100 + 147355321 = 40810^2 + 12139^2 .

It is an emirp because it is prime and its reverse (1241182181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1812811421 - 2¹⁴ = 1812795037 is a prime.

It is a Sophie Germain prime.

Together with 1812811423, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1812811423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 906405710 + 906405711.

It is an arithmetic number, because the mean of its divisors is an integer number (906405711).

Almost surely, 2^1812811421 is an apocalyptic number.

It is an amenable number.

1812811421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1812811421 is an equidigital number, since it uses as much as digits as its factorization.

1812811421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1024, while the sum is 29.

The square root of 1812811421 is about 42577.1232118846. The cubic root of 1812811421 is about 1219.3195661495.

The spelling of 1812811421 in words is "one billion, eight hundred twelve million, eight hundred eleven thousand, four hundred twenty-one".