16688291221 has 4 divisors (see below), whose sum is σ = 19072332832. Its totient is φ = 14304249612.

The previous prime is 16688291219. The next prime is 16688291227. The reversal of 16688291221 is 12219288661.

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: 12219288661 = 38047 ⋅321163.

It is a cyclic number.

It is not a de Polignac number, because 16688291221 - 2¹ = 16688291219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16688291227) 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 in 3 ways as a sum of consecutive naturals, for example, 1192020795 + ... + 1192020808.

It is an arithmetic number, because the mean of its divisors is an integer number (4768083208).

Almost surely, 2^16688291221 is an apocalyptic number.

It is an amenable number.

16688291221 is a deficient number, since it is larger than the sum of its proper divisors (2384041611).

16688291221 is an equidigital number, since it uses as much as digits as its factorization.

16688291221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2384041610.

The product of its digits is 165888, while the sum is 46.

The spelling of 16688291221 in words is "sixteen billion, six hundred eighty-eight million, two hundred ninety-one thousand, two hundred twenty-one".