1921544687369 has 2 divisors, whose sum is σ = 1921544687370. Its totient is φ = 1921544687368.

The previous prime is 1921544687353. The next prime is 1921544687389. The reversal of 1921544687369 is 9637864451291.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1444775152144 + 476769535225 = 1201988^2 + 690485^2 .

It is a cyclic number.

It is not a de Polignac number, because 1921544687369 - 2⁴ = 1921544687353 is a prime.

It is a super-2 number, since 2×1921544687369² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1921544687329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960772343684 + 960772343685.

It is an arithmetic number, because the mean of its divisors is an integer number (960772343685).

Almost surely, 2^{1921544687369} is an apocalyptic number.

It is an amenable number.

1921544687369 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921544687369 is an equidigital number, since it uses as much as digits as its factorization.

1921544687369 is an evil number, because the sum of its binary digits is even.

The product of its digits is 78382080, while the sum is 65.

The spelling of 1921544687369 in words is "one trillion, nine hundred twenty-one billion, five hundred forty-four million, six hundred eighty-seven thousand, three hundred sixty-nine".