16550717921 has 4 divisors (see below), whose sum is σ = 16551068352. Its totient is φ = 16550367492.

The previous prime is 16550717903. The next prime is 16550717929. The reversal of 16550717921 is 12971705561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12971705561 = 173 ⋅74980957.

It is a cyclic number.

It is not a de Polignac number, because 16550717921 - 2¹⁸ = 16550455777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16550717929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90821 + ... + 203346.

It is an arithmetic number, because the mean of its divisors is an integer number (4137767088).

Almost surely, 2^16550717921 is an apocalyptic number.

It is an amenable number.

16550717921 is a deficient number, since it is larger than the sum of its proper divisors (350431).

16550717921 is an equidigital number, since it uses as much as digits as its factorization.

16550717921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350430.

The product of its (nonzero) digits is 132300, while the sum is 44.

The spelling of 16550717921 in words is "sixteen billion, five hundred fifty million, seven hundred seventeen thousand, nine hundred twenty-one".