1221111221001 has 16 divisors (see below), whose sum is σ = 1911031204224. Its totient is φ = 678918979584.

The previous prime is 1221111220999. The next prime is 1221111221017. The reversal of 1221111221001 is 1001221111221.

It is a happy number.

It is not a de Polignac number, because 1221111221001 - 2¹ = 1221111220999 is a prime.

It is a super-2 number, since 2×1221111221001² (a number of 25 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1221111221021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 785785080 + ... + 785786633.

It is an arithmetic number, because the mean of its divisors is an integer number (119439450264).

Almost surely, 2^{1221111221001} is an apocalyptic number.

It is an amenable number.

1221111221001 is a deficient number, since it is larger than the sum of its proper divisors (689919983223).

1221111221001 is a wasteful number, since it uses less digits than its factorization.

1221111221001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1571571760.

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

Adding to 1221111221001 its reverse (1001221111221), we get a palindrome (2222332332222).

The spelling of 1221111221001 in words is "one trillion, two hundred twenty-one billion, one hundred eleven million, two hundred twenty-one thousand, one".