221005009 has 4 divisors (see below), whose sum is σ = 221111716. Its totient is φ = 220898304.

The previous prime is 221005007. The next prime is 221005051. The reversal of 221005009 is 900500122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 900500122 = 2 ⋅450250061.

It can be written as a sum of positive squares in 2 ways, for example, as 32547025 + 188457984 = 5705^2 + 13728^2 .

It is a cyclic number.

It is not a de Polignac number, because 221005009 - 2¹ = 221005007 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221005003) 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, 50184 + ... + 54409.

It is an arithmetic number, because the mean of its divisors is an integer number (55277929).

Almost surely, 2^221005009 is an apocalyptic number.

It is an amenable number.

221005009 is a deficient number, since it is larger than the sum of its proper divisors (106707).

221005009 is a wasteful number, since it uses less digits than its factorization.

221005009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106706.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 221005009 is about 14866.2372172652. The cubic root of 221005009 is about 604.5989273090.

The spelling of 221005009 in words is "two hundred twenty-one million, five thousand, nine".