1220505521 has 2 divisors, whose sum is σ = 1220505522. Its totient is φ = 1220505520.

The previous prime is 1220505509. The next prime is 1220505551. The reversal of 1220505521 is 1255050221.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 786241600 + 434263921 = 28040^2 + 20839^2 .

It is a cyclic number.

It is not a de Polignac number, because 1220505521 - 2¹⁰ = 1220504497 is a prime.

It is not a weakly prime, because it can be changed into another prime (1220505551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610252760 + 610252761.

It is an arithmetic number, because the mean of its divisors is an integer number (610252761).

Almost surely, 2^1220505521 is an apocalyptic number.

It is an amenable number.

1220505521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1220505521 is an equidigital number, since it uses as much as digits as its factorization.

1220505521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 1220505521 is about 34935.7341557323. The cubic root of 1220505521 is about 1068.6772956208.

Adding to 1220505521 its reverse (1255050221), we get a palindrome (2475555742).

The spelling of 1220505521 in words is "one billion, two hundred twenty million, five hundred five thousand, five hundred twenty-one".