16166555560021 has 4 divisors (see below), whose sum is σ = 16167286802700. Its totient is φ = 16165824317344.

The previous prime is 16166555560013. The next prime is 16166555560027. The reversal of 16166555560021 is 12006555566161.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5616473408100 + 10550082151921 = 2369910^2 + 3248089^2 .

It is a cyclic number.

It is not a de Polignac number, because 16166555560021 - 2³ = 16166555560013 is a prime.

It is a super-2 number, since 2×16166555560021² (a number of 27 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16166555560027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365588176 + ... + 365632393.

It is an arithmetic number, because the mean of its divisors is an integer number (4041821700675).

Almost surely, 2^{16166555560021} is an apocalyptic number.

It is an amenable number.

16166555560021 is a deficient number, since it is larger than the sum of its proper divisors (731242679).

16166555560021 is an equidigital number, since it uses as much as digits as its factorization.

16166555560021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731242678.

The product of its (nonzero) digits is 1620000, while the sum is 49.

The spelling of 16166555560021 in words is "sixteen trillion, one hundred sixty-six billion, five hundred fifty-five million, five hundred sixty thousand, twenty-one".