16506555561601 has 6 divisors (see below), whose sum is σ = 19201503408450. Its totient is φ = 14148476195616.

The previous prime is 16506555561593. The next prime is 16506555561679. The reversal of 16506555561601 is 10616555560561.

It can be written as a sum of positive squares in only one way, i.e., 12823990723600 + 3682564838001 = 3581060^2 + 1919001^2 .

It is not a de Polignac number, because 16506555561601 - 2³ = 16506555561593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16506555561701) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 168434240376 + ... + 168434240473.

It is an arithmetic number, because the mean of its divisors is an integer number (3200250568075).

Almost surely, 2^{16506555561601} is an apocalyptic number.

It is an amenable number.

16506555561601 is a deficient number, since it is larger than the sum of its proper divisors (2694947846849).

16506555561601 is an equidigital number, since it uses as much as digits as its factorization.

16506555561601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336868480863 (or 336868480856 counting only the distinct ones).

The product of its (nonzero) digits is 4050000, while the sum is 52.

The spelling of 16506555561601 in words is "sixteen trillion, five hundred six billion, five hundred fifty-five million, five hundred sixty-one thousand, six hundred one".