1221220001 has 2 divisors, whose sum is σ = 1221220002. Its totient is φ = 1221220000.

The previous prime is 1221219971. The next prime is 1221220027. The reversal of 1221220001 is 1000221221.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 612315025 + 608904976 = 24745^2 + 24676^2 .

It is an emirp because it is prime and its reverse (1000221221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221220001 - 2²⁶ = 1154111137 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221220031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610610000 + 610610001.

It is an arithmetic number, because the mean of its divisors is an integer number (610610001).

Almost surely, 2^1221220001 is an apocalyptic number.

It is an amenable number.

1221220001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221220001 is an equidigital number, since it uses as much as digits as its factorization.

1221220001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1221220001 is about 34945.9582927697. The cubic root of 1221220001 is about 1068.8857883577.

Adding to 1221220001 its reverse (1000221221), we get a palindrome (2221441222).

The spelling of 1221220001 in words is "one billion, two hundred twenty-one million, two hundred twenty thousand, one".