16587221 has 4 divisors (see below), whose sum is σ = 18956832. Its totient is φ = 14217612.

The previous prime is 16587187. The next prime is 16587227. The reversal of 16587221 is 12278561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16587221 - 2¹⁸ = 16325077 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16587227) 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, 1184795 + ... + 1184808.

It is an arithmetic number, because the mean of its divisors is an integer number (4739208).

Almost surely, 2^16587221 is an apocalyptic number.

It is an amenable number.

16587221 is a deficient number, since it is larger than the sum of its proper divisors (2369611).

16587221 is an equidigital number, since it uses as much as digits as its factorization.

16587221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2369610.

The product of its digits is 6720, while the sum is 32.

The square root of 16587221 is about 4072.7412144648. The cubic root of 16587221 is about 255.0299644399.

The spelling of 16587221 in words is "sixteen million, five hundred eighty-seven thousand, two hundred twenty-one".