1221121211001 has 64 divisors (see below), whose sum is σ = 1716476805120. Its totient is φ = 771394440960.

The previous prime is 1221121210993. The next prime is 1221121211021. The reversal of 1221121211001 is 1001121211221.

It is a happy number.

It is not a de Polignac number, because 1221121211001 - 2³ = 1221121210993 is a prime.

It is a super-2 number, since 2×1221121211001² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221121211021) 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 63 ways as a sum of consecutive naturals, for example, 721275711 + ... + 721277403.

It is an arithmetic number, because the mean of its divisors is an integer number (26819950080).

Almost surely, 2^{1221121211001} is an apocalyptic number.

It is an amenable number.

1221121211001 is a deficient number, since it is larger than the sum of its proper divisors (495355594119).

1221121211001 is a wasteful number, since it uses less digits than its factorization.

1221121211001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2886.

The product of its (nonzero) digits is 16, while the sum is 15.

Adding to 1221121211001 its reverse (1001121211221), we get a palindrome (2222242422222).

The spelling of 1221121211001 in words is "one trillion, two hundred twenty-one billion, one hundred twenty-one million, two hundred eleven thousand, one".