1211121210221 has 4 divisors (see below), whose sum is σ = 1304284380252. Its totient is φ = 1117958040192.

The previous prime is 1211121210073. The next prime is 1211121210251. The reversal of 1211121210221 is 1220121211121.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 701717834596 + 509403375625 = 837686^2 + 713725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211121210221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1211121210221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211121210251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46581584996 + ... + 46581585021.

It is an arithmetic number, because the mean of its divisors is an integer number (326071095063).

Almost surely, 2^{1211121210221} is an apocalyptic number.

It is an amenable number.

1211121210221 is a deficient number, since it is larger than the sum of its proper divisors (93163170031).

1211121210221 is an equidigital number, since it uses as much as digits as its factorization.

1211121210221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 93163170030.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 1211121210221 its reverse (1220121211121), we get a palindrome (2431242421342).

The spelling of 1211121210221 in words is "one trillion, two hundred eleven billion, one hundred twenty-one million, two hundred ten thousand, two hundred twenty-one".