16988821 has 4 divisors (see below), whose sum is σ = 17032012. Its totient is φ = 16945632.

The previous prime is 16988819. The next prime is 16988843. The reversal of 16988821 is 12888961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12888961 = 547 ⋅23563.

It can be written as a sum of positive squares in 2 ways, for example, as 10150596 + 6838225 = 3186^2 + 2615^2 .

It is a cyclic number.

It is not a de Polignac number, because 16988821 - 2¹ = 16988819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16988891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21000 + ... + 21793.

It is an arithmetic number, because the mean of its divisors is an integer number (4258003).

Almost surely, 2^16988821 is an apocalyptic number.

It is an amenable number.

16988821 is a deficient number, since it is larger than the sum of its proper divisors (43191).

16988821 is an equidigital number, since it uses as much as digits as its factorization.

16988821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43190.

The product of its digits is 55296, while the sum is 43.

The square root of 16988821 is about 4121.7497498029. The cubic root of 16988821 is about 257.0717852230.

The spelling of 16988821 in words is "sixteen million, nine hundred eighty-eight thousand, eight hundred twenty-one".