1220215565 has 4 divisors (see below), whose sum is σ = 1464258684. Its totient is φ = 976172448.

The previous prime is 1220215561. The next prime is 1220215567. The reversal of 1220215565 is 5655120221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 432515209 + 787700356 = 20797^2 + 28066^2 .

It is a cyclic number.

It is not a de Polignac number, because 1220215565 - 2² = 1220215561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220215561) 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 in 3 ways as a sum of consecutive naturals, for example, 122021552 + ... + 122021561.

It is an arithmetic number, because the mean of its divisors is an integer number (366064671).

Almost surely, 2^1220215565 is an apocalyptic number.

It is an amenable number.

1220215565 is a deficient number, since it is larger than the sum of its proper divisors (244043119).

1220215565 is an equidigital number, since it uses as much as digits as its factorization.

1220215565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244043118.

The product of its (nonzero) digits is 6000, while the sum is 29.

The square root of 1220215565 is about 34931.5840608467. The cubic root of 1220215565 is about 1068.5926602162.

Adding to 1220215565 its reverse (5655120221), we get a palindrome (6875335786).

The spelling of 1220215565 in words is "one billion, two hundred twenty million, two hundred fifteen thousand, five hundred sixty-five".