1221211110001 has 2 divisors, whose sum is σ = 1221211110002. Its totient is φ = 1221211110000.

The previous prime is 1221211109977. The next prime is 1221211110061. The reversal of 1221211110001 is 1000111121221.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 661048676401 + 560162433600 = 813049^2 + 748440^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221211110001 - 2³¹ = 1219063626353 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221211110061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610605555000 + 610605555001.

It is an arithmetic number, because the mean of its divisors is an integer number (610605555001).

Almost surely, 2^{1221211110001} is an apocalyptic number.

It is an amenable number.

1221211110001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221211110001 is an equidigital number, since it uses as much as digits as its factorization.

1221211110001 is an evil number, because the sum of its binary digits is even.

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

Adding to 1221211110001 its reverse (1000111121221), we get a palindrome (2221322231222).

The spelling of 1221211110001 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, one hundred ten thousand, one".