16556510001681 has 48 divisors (see below), whose sum is σ = 26646435925200. Its totient is φ = 9835895494656.

The previous prime is 16556510001641. The next prime is 16556510001719. The reversal of 16556510001681 is 18610001565561.

16556510001681 is a `hidden beast` number, since 1 + 6 + 5 + 56 + 510 + 0 + 0 + 1 + 6 + 81 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 2327809312656 + 14228700689025 = 1525716^2 + 3772095^2 .

It is not a de Polignac number, because 16556510001681 - 2¹⁴ = 16556509985297 is a prime.

It is a super-2 number, since 2×16556510001681² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (16556510001641) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 23846461 + ... + 24530933.

It is an arithmetic number, because the mean of its divisors is an integer number (555134081775).

Almost surely, 2^{16556510001681} is an apocalyptic number.

It is an amenable number.

16556510001681 is a deficient number, since it is larger than the sum of its proper divisors (10089925923519).

16556510001681 is a wasteful number, since it uses less digits than its factorization.

16556510001681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 691650 (or 691647 counting only the distinct ones).

The product of its (nonzero) digits is 216000, while the sum is 45.

The spelling of 16556510001681 in words is "sixteen trillion, five hundred fifty-six billion, five hundred ten million, one thousand, six hundred eighty-one".