1821678689 has 2 divisors, whose sum is σ = 1821678690. Its totient is φ = 1821678688.

The previous prime is 1821678679. The next prime is 1821678731. The reversal of 1821678689 is 9868761281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1812630625 + 9048064 = 42575^2 + 3008^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1821678689 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1821678629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910839344 + 910839345.

It is an arithmetic number, because the mean of its divisors is an integer number (910839345).

Almost surely, 2^1821678689 is an apocalyptic number.

It is an amenable number.

1821678689 is a deficient number, since it is larger than the sum of its proper divisors (1).

1821678689 is an equidigital number, since it uses as much as digits as its factorization.

1821678689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2322432, while the sum is 56.

The square root of 1821678689 is about 42681.1280193015. The cubic root of 1821678689 is about 1221.3044117458.

The spelling of 1821678689 in words is "one billion, eight hundred twenty-one million, six hundred seventy-eight thousand, six hundred eighty-nine".