1661555556596 has 36 divisors (see below), whose sum is σ = 3148858294092. Its totient is φ = 766808550144.

The previous prime is 1661555556581. The next prime is 1661555556599. The reversal of 1661555556596 is 6956555551661.

It can be written as a sum of positive squares in 6 ways, for example, as 308009460196 + 1353546096400 = 554986^2 + 1163420^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661555556599) 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, 8661350 + ... + 8851106.

It is an arithmetic number, because the mean of its divisors is an integer number (87468285947).

Almost surely, 2^{1661555556596} is an apocalyptic number.

It is an amenable number.

1661555556596 is a deficient number, since it is larger than the sum of its proper divisors (1487302737496).

1661555556596 is a wasteful number, since it uses less digits than its factorization.

1661555556596 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202740 (or 202725 counting only the distinct ones).

The product of its digits is 182250000, while the sum is 65.

The spelling of 1661555556596 in words is "one trillion, six hundred sixty-one billion, five hundred fifty-five million, five hundred fifty-six thousand, five hundred ninety-six".