1221000221 has 16 divisors (see below), whose sum is σ = 1437081600. Its totient is φ = 1015782768.

The previous prime is 1221000203. The next prime is 1221000227. The reversal of 1221000221 is 1220001221.

It is a happy number.

It is not a de Polignac number, because 1221000221 - 2²⁶ = 1153891357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221000227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13916 + ... + 51338.

It is an arithmetic number, because the mean of its divisors is an integer number (89817600).

Almost surely, 2^1221000221 is an apocalyptic number.

It is an amenable number.

1221000221 is a deficient number, since it is larger than the sum of its proper divisors (216081379).

1221000221 is an equidigital number, since it uses as much as digits as its factorization.

1221000221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37568.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1221000221 is about 34942.8135816222. The cubic root of 1221000221 is about 1068.8216629169.

Adding to 1221000221 its reverse (1220001221), we get a palindrome (2441001442).

It can be divided in two parts, 1221000 and 221, that added together give a palindrome (1221221).

The spelling of 1221000221 in words is "one billion, two hundred twenty-one million, two hundred twenty-one", and thus it is an aban number.