1211020221 has 4 divisors (see below), whose sum is σ = 1614693632. Its totient is φ = 807346812.

The previous prime is 1211020207. The next prime is 1211020229. The reversal of 1211020221 is 1220201121.

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 not a de Polignac number, because 1211020221 - 2⁹ = 1211019709 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1211020197 and 1211020206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211020229) 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, 201836701 + ... + 201836706.

It is an arithmetic number, because the mean of its divisors is an integer number (403673408).

Almost surely, 2^1211020221 is an apocalyptic number.

It is an amenable number.

1211020221 is a deficient number, since it is larger than the sum of its proper divisors (403673411).

1211020221 is an equidigital number, since it uses as much as digits as its factorization.

1211020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403673410.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 1211020221 is about 34799.7158178052. The cubic root of 1211020221 is about 1065.9016429309.

Adding to 1211020221 its reverse (1220201121), we get a palindrome (2431221342).

Subtracting 1211020221 from its reverse (1220201121), we obtain a square (9180900 = 3030²).

The spelling of 1211020221 in words is "one billion, two hundred eleven million, twenty thousand, two hundred twenty-one".