1989366381601 has 3 divisors (see below), whose sum is σ = 1989367792051. Its totient is φ = 1989364971152.

The previous prime is 1989366381553. The next prime is 1989366381643. The reversal of 1989366381601 is 1061836639891.

The square root of 1989366381601 is 1410449.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1737121364001 + 252245017600 = 1317999^2 + 502240^2 .

It is not a de Polignac number, because 1989366381601 - 2⁷ = 1989366381473 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1989366381601.

It is not an unprimeable number, because it can be changed into a prime (1989366384601) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 705225 + ... + 2115673.

Almost surely, 2^{1989366381601} is an apocalyptic number.

1989366381601 is the 1410449-th square number.

1989366381601 is the 705225-th centered octagonal number.

It is an amenable number.

1989366381601 is a deficient number, since it is larger than the sum of its proper divisors (1410450).

1989366381601 is an frugal number, since it uses more digits than its factorization.

1989366381601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2820898 (or 1410449 counting only the distinct ones).

The product of its (nonzero) digits is 10077696, while the sum is 61.

The spelling of 1989366381601 in words is "one trillion, nine hundred eighty-nine billion, three hundred sixty-six million, three hundred eighty-one thousand, six hundred one".