1211201221 has 4 divisors (see below), whose sum is σ = 1212039712. Its totient is φ = 1210362732.

The previous prime is 1211201207. The next prime is 1211201237. The reversal of 1211201221 is 1221021121.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1221021121 = 2341 ⋅521581.

It is a cyclic number.

It is not a de Polignac number, because 1211201221 - 2¹¹ = 1211199173 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 (1211201291) 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, 417075 + ... + 419968.

It is an arithmetic number, because the mean of its divisors is an integer number (303009928).

Almost surely, 2^1211201221 is an apocalyptic number.

It is an amenable number.

1211201221 is a deficient number, since it is larger than the sum of its proper divisors (838491).

1211201221 is an equidigital number, since it uses as much as digits as its factorization.

1211201221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 838490.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 1211201221 is about 34802.3163165902. The cubic root of 1211201221 is about 1065.9547437746.

Adding to 1211201221 its reverse (1221021121), we get a palindrome (2432222342).

The spelling of 1211201221 in words is "one billion, two hundred eleven million, two hundred one thousand, two hundred twenty-one".