221968009 has 4 divisors (see below), whose sum is σ = 231618816. Its totient is φ = 212317204.

The previous prime is 221968007. The next prime is 221968027. The reversal of 221968009 is 900869122.

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, and also an emirpimes, since its reverse is a distinct semiprime: 900869122 = 2 ⋅450434561.

It is a cyclic number.

It is not a de Polignac number, because 221968009 - 2¹ = 221968007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221968007) 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, 4825369 + ... + 4825414.

It is an arithmetic number, because the mean of its divisors is an integer number (57904704).

Almost surely, 2^221968009 is an apocalyptic number.

It is an amenable number.

221968009 is a deficient number, since it is larger than the sum of its proper divisors (9650807).

221968009 is an equidigital number, since it uses as much as digits as its factorization.

221968009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9650806.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 221968009 is about 14898.5908394049. The cubic root of 221968009 is about 605.4758081081.

The spelling of 221968009 in words is "two hundred twenty-one million, nine hundred sixty-eight thousand, nine".