16655621 has 4 divisors (see below), whose sum is σ = 16969932. Its totient is φ = 16341312.

The previous prime is 16655593. The next prime is 16655633. The reversal of 16655621 is 12655661.

16655621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12655661 = 113 ⋅111997.

It can be written as a sum of positive squares in 2 ways, for example, as 7230721 + 9424900 = 2689^2 + 3070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16655621 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 (16655651) 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, 157076 + ... + 157181.

It is an arithmetic number, because the mean of its divisors is an integer number (4242483).

Almost surely, 2^16655621 is an apocalyptic number.

It is an amenable number.

16655621 is a deficient number, since it is larger than the sum of its proper divisors (314311).

16655621 is an equidigital number, since it uses as much as digits as its factorization.

16655621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314310.

The product of its digits is 10800, while the sum is 32.

The square root of 16655621 is about 4081.1298680635. The cubic root of 16655621 is about 255.3800356702.

The spelling of 16655621 in words is "sixteen million, six hundred fifty-five thousand, six hundred twenty-one".