1221518101 has 2 divisors, whose sum is σ = 1221518102. Its totient is φ = 1221518100.

The previous prime is 1221518047. The next prime is 1221518117. The reversal of 1221518101 is 1018151221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 796086225 + 425431876 = 28215^2 + 20626^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221518101 - 2⁹ = 1221517589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221518191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610759050 + 610759051.

It is an arithmetic number, because the mean of its divisors is an integer number (610759051).

Almost surely, 2^1221518101 is an apocalyptic number.

It is an amenable number.

1221518101 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221518101 is an equidigital number, since it uses as much as digits as its factorization.

1221518101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 160, while the sum is 22.

The square root of 1221518101 is about 34950.2231895592. The cubic root of 1221518101 is about 1068.9727530134.

Adding to 1221518101 its reverse (1018151221), we get a palindrome (2239669322).

The spelling of 1221518101 in words is "one billion, two hundred twenty-one million, five hundred eighteen thousand, one hundred one".