16897621 has 4 divisors (see below), whose sum is σ = 18197452. Its totient is φ = 15597792.

The previous prime is 16897591. The next prime is 16897627. The reversal of 16897621 is 12679861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12679861 = 109 ⋅116329.

It can be written as a sum of positive squares in 2 ways, for example, as 7349521 + 9548100 = 2711^2 + 3090^2 .

It is a cyclic number.

It is not a de Polignac number, because 16897621 - 2⁵ = 16897589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16897627) 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, 649896 + ... + 649921.

It is an arithmetic number, because the mean of its divisors is an integer number (4549363).

Almost surely, 2^16897621 is an apocalyptic number.

It is an amenable number.

16897621 is a deficient number, since it is larger than the sum of its proper divisors (1299831).

16897621 is a wasteful number, since it uses less digits than its factorization.

16897621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1299830.

The product of its digits is 36288, while the sum is 40.

The square root of 16897621 is about 4110.6715996294. The cubic root of 16897621 is about 256.6109522817.

The spelling of 16897621 in words is "sixteen million, eight hundred ninety-seven thousand, six hundred twenty-one".