1944888865921 has 2 divisors, whose sum is σ = 1944888865922. Its totient is φ = 1944888865920.

The previous prime is 1944888865873. The next prime is 1944888865991. The reversal of 1944888865921 is 1295688884491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1912744320400 + 32144545521 = 1383020^2 + 179289^2 .

It is an emirp because it is prime and its reverse (1295688884491) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1944888865921 - 2³⁷ = 1807449912449 is a prime.

It is not a weakly prime, because it can be changed into another prime (1944888865991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 972444432960 + 972444432961.

It is an arithmetic number, because the mean of its divisors is an integer number (972444432961).

Almost surely, 2^{1944888865921} is an apocalyptic number.

It is an amenable number.

1944888865921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1944888865921 is an equidigital number, since it uses as much as digits as its factorization.

1944888865921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 318504960, while the sum is 73.

The spelling of 1944888865921 in words is "one trillion, nine hundred forty-four billion, eight hundred eighty-eight million, eight hundred sixty-five thousand, nine hundred twenty-one".