1000001221 has 4 divisors (see below), whose sum is σ = 1005588000. Its totient is φ = 994414444.

The previous prime is 1000001213. The next prime is 1000001237. The reversal of 1000001221 is 1221000001.

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 1000001221 - 2³ = 1000001213 is a prime.

It is a Duffinian number.

1000001221 is a modest number, since divided by 1221 gives 1000 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1000001021) 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, 2793121 + ... + 2793478.

It is an arithmetic number, because the mean of its divisors is an integer number (251397000).

Almost surely, 2^1000001221 is an apocalyptic number.

It is an amenable number.

1000001221 is a deficient number, since it is larger than the sum of its proper divisors (5586779).

1000001221 is an equidigital number, since it uses as much as digits as its factorization.

1000001221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5586778.

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

The square root of 1000001221 is about 31622.7959073830. The cubic root of 1000001221 is about 1000.0004069998. Note that the first 3 decimals are identical.

Adding to 1000001221 its reverse (1221000001), we get a palindrome (2221001222).

The spelling of 1000001221 in words is "one billion, one thousand, two hundred twenty-one".