1221221111001 has 8 divisors (see below), whose sum is σ = 1672302782784. Its totient is φ = 792143423280.

The previous prime is 1221221110937. The next prime is 1221221111053. The reversal of 1221221111001 is 1001111221221.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221221111001 - 2⁶ = 1221221110937 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221221111501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5500995885 + ... + 5500996106.

It is an arithmetic number, because the mean of its divisors is an integer number (209037847848).

Almost surely, 2^{1221221111001} is an apocalyptic number.

It is an amenable number.

1221221111001 is a deficient number, since it is larger than the sum of its proper divisors (451081671783).

1221221111001 is a wasteful number, since it uses less digits than its factorization.

1221221111001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11001992031.

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

Adding to 1221221111001 its reverse (1001111221221), we get a palindrome (2222332332222).

The spelling of 1221221111001 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, one".