16897921 has 4 divisors (see below), whose sum is σ = 16908100. Its totient is φ = 16887744.

The previous prime is 16897913. The next prime is 16897963. The reversal of 16897921 is 12979861.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12979861 = 97 ⋅133813.

It can be written as a sum of positive squares in 2 ways, for example, as 6426225 + 10471696 = 2535^2 + 3236^2 .

It is a cyclic number.

It is not a de Polignac number, because 16897921 - 2³ = 16897913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16897901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1956 + ... + 6133.

It is an arithmetic number, because the mean of its divisors is an integer number (4227025).

Almost surely, 2^16897921 is an apocalyptic number.

It is an amenable number.

16897921 is a deficient number, since it is larger than the sum of its proper divisors (10179).

16897921 is an equidigital number, since it uses as much as digits as its factorization.

16897921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10178.

The product of its digits is 54432, while the sum is 43.

The square root of 16897921 is about 4110.7080898551. The cubic root of 16897921 is about 256.6124708945.

It can be divided in two parts, 168 and 97921, that added together give a palindrome (98089).

The spelling of 16897921 in words is "sixteen million, eight hundred ninety-seven thousand, nine hundred twenty-one".