1211221101001 has 4 divisors (see below), whose sum is σ = 1211225410000. Its totient is φ = 1211216792004.

The previous prime is 1211221100959. The next prime is 1211221101091. The reversal of 1211221101001 is 1001011221121.

It is a happy number.

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 1211221101001 - 2⁹ = 1211221100489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1211221101091) 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, 1701051 + ... + 2305648.

It is an arithmetic number, because the mean of its divisors is an integer number (302806352500).

Almost surely, 2^{1211221101001} is an apocalyptic number.

It is an amenable number.

1211221101001 is a deficient number, since it is larger than the sum of its proper divisors (4308999).

1211221101001 is an equidigital number, since it uses as much as digits as its factorization.

1211221101001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4308998.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 1211221101001 its reverse (1001011221121), we get a palindrome (2212232322122).

The spelling of 1211221101001 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, one hundred one thousand, one".