1665939818637 has 12 divisors (see below), whose sum is σ = 2406378085020. Its totient is φ = 1110617052288.

The previous prime is 1665939818633. The next prime is 1665939818639. The reversal of 1665939818637 is 7368189395661.

1665939818637 is a `hidden beast` number, since 1 + 6 + 6 + 59 + 398 + 186 + 3 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 553634212356 + 1112305606281 = 744066^2 + 1054659^2 .

It is not a de Polignac number, because 1665939818637 - 2² = 1665939818633 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665939818633) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 417439 + ... + 1872467.

It is an arithmetic number, because the mean of its divisors is an integer number (200531507085).

Almost surely, 2^{1665939818637} is an apocalyptic number.

It is an amenable number.

1665939818637 is a deficient number, since it is larger than the sum of its proper divisors (740438266383).

1665939818637 is a wasteful number, since it uses less digits than its factorization.

1665939818637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1582252 (or 1582249 counting only the distinct ones).

The product of its digits is 352719360, while the sum is 72.

The spelling of 1665939818637 in words is "one trillion, six hundred sixty-five billion, nine hundred thirty-nine million, eight hundred eighteen thousand, six hundred thirty-seven".