100001221 has 4 divisors (see below), whose sum is σ = 100041100. Its totient is φ = 99961344.

The previous prime is 100001219. The next prime is 100001227. The reversal of 100001221 is 122100001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122100001 = 17 ⋅7182353.

It can be written as a sum of positive squares in 2 ways, for example, as 42393121 + 57608100 = 6511^2 + 7590^2 .

It is a cyclic number.

It is not a de Polignac number, because 100001221 - 2¹ = 100001219 is a prime.

It is a Duffinian number.

100001221 is a modest number, since divided by 1221 gives 100 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100001227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15906 + ... + 21283.

It is an arithmetic number, because the mean of its divisors is an integer number (25010275).

Almost surely, 2^100001221 is an apocalyptic number.

It is an amenable number.

100001221 is a deficient number, since it is larger than the sum of its proper divisors (39879).

100001221 is an equidigital number, since it uses as much as digits as its factorization.

100001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39878.

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 100001221 is about 10000.0610498136. The cubic root of 100001221 is about 464.1607724802.

Adding to 100001221 its reverse (122100001), we get a palindrome (222101222).

The spelling of 100001221 in words is "one hundred million, one thousand, two hundred twenty-one".