16566531481 has 2 divisors, whose sum is σ = 16566531482. Its totient is φ = 16566531480.

The previous prime is 16566531469. The next prime is 16566531539. The reversal of 16566531481 is 18413566561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14213408400 + 2353123081 = 119220^2 + 48509^2 .

It is a cyclic number.

It is not a de Polignac number, because 16566531481 - 2⁹ = 16566530969 is a prime.

It is a super-3 number, since 3×16566531481³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (16566538481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8283265740 + 8283265741.

It is an arithmetic number, because the mean of its divisors is an integer number (8283265741).

Almost surely, 2^16566531481 is an apocalyptic number.

It is an amenable number.

16566531481 is a deficient number, since it is larger than the sum of its proper divisors (1).

16566531481 is an equidigital number, since it uses as much as digits as its factorization.

16566531481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 518400, while the sum is 46.

The spelling of 16566531481 in words is "sixteen billion, five hundred sixty-six million, five hundred thirty-one thousand, four hundred eighty-one".