16551537881 has 2 divisors, whose sum is σ = 16551537882. Its totient is φ = 16551537880.

The previous prime is 16551537829. The next prime is 16551537917. The reversal of 16551537881 is 18873515561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11254027225 + 5297510656 = 106085^2 + 72784^2 .

It is an emirp because it is prime and its reverse (18873515561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 16551537881 - 2¹⁸ = 16551275737 is a prime.

It is a super-2 number, since 2×16551537881² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (16551537781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8275768940 + 8275768941.

It is an arithmetic number, because the mean of its divisors is an integer number (8275768941).

Almost surely, 2^16551537881 is an apocalyptic number.

It is an amenable number.

16551537881 is a deficient number, since it is larger than the sum of its proper divisors (1).

16551537881 is an equidigital number, since it uses as much as digits as its factorization.

16551537881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008000, while the sum is 50.

The spelling of 16551537881 in words is "sixteen billion, five hundred fifty-one million, five hundred thirty-seven thousand, eight hundred eighty-one".