1815895664789 has 2 divisors, whose sum is σ = 1815895664790. Its totient is φ = 1815895664788.

The previous prime is 1815895664783. The next prime is 1815895664873. The reversal of 1815895664789 is 9874665985181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1811021530564 + 4874134225 = 1345742^2 + 69815^2 .

It is a cyclic number.

It is not a de Polignac number, because 1815895664789 - 2⁴ = 1815895664773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1815895664783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 907947832394 + 907947832395.

It is an arithmetic number, because the mean of its divisors is an integer number (907947832395).

Almost surely, 2^{1815895664789} is an apocalyptic number.

It is an amenable number.

1815895664789 is a deficient number, since it is larger than the sum of its proper divisors (1).

1815895664789 is an equidigital number, since it uses as much as digits as its factorization.

1815895664789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1045094400, while the sum is 77.

The spelling of 1815895664789 in words is "one trillion, eight hundred fifteen billion, eight hundred ninety-five million, six hundred sixty-four thousand, seven hundred eighty-nine".