16620161 has 4 divisors (see below), whose sum is σ = 17193300. Its totient is φ = 16047024.

The previous prime is 16620157. The next prime is 16620173. The reversal of 16620161 is 16102661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16102661 = 179 ⋅89959.

It can be written as a sum of positive squares in 2 ways, for example, as 12559936 + 4060225 = 3544^2 + 2015^2 .

It is a cyclic number.

It is not a de Polignac number, because 16620161 - 2² = 16620157 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16620361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286526 + ... + 286583.

It is an arithmetic number, because the mean of its divisors is an integer number (4298325).

Almost surely, 2^16620161 is an apocalyptic number.

It is an amenable number.

16620161 is a deficient number, since it is larger than the sum of its proper divisors (573139).

16620161 is an equidigital number, since it uses as much as digits as its factorization.

16620161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573138.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 16620161 is about 4076.7831681364. The cubic root of 16620161 is about 255.1986712669.

The spelling of 16620161 in words is "sixteen million, six hundred twenty thousand, one hundred sixty-one".