221649 has 4 divisors (see below), whose sum is σ = 295536. Its totient is φ = 147764.

The previous prime is 221623. The next prime is 221653. The reversal of 221649 is 946122.

221649 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 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 221649 - 2⁸ = 221393 is a prime.

It is a D-number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221649.

It is not an unprimeable number, because it can be changed into a prime (221659) 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, 36939 + ... + 36944.

It is an arithmetic number, because the mean of its divisors is an integer number (73884).

2²²¹⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

221649 is a deficient number, since it is larger than the sum of its proper divisors (73887).

221649 is an equidigital number, since it uses as much as digits as its factorization.

221649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73886.

The product of its digits is 864, while the sum is 24.

The square root of 221649 is about 470.7961342237. The cubic root of 221649 is about 60.5185608875.

The spelling of 221649 in words is "two hundred twenty-one thousand, six hundred forty-nine".