1221565 has 4 divisors (see below), whose sum is σ = 1465884. Its totient is φ = 977248.

The previous prime is 1221559. The next prime is 1221589. The reversal of 1221565 is 5651221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5651221 = 83 ⋅68087.

It can be written as a sum of positive squares in 2 ways, for example, as 127449 + 1094116 = 357^2 + 1046^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221565 - 2³ = 1221557 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 122152 + ... + 122161.

It is an arithmetic number, because the mean of its divisors is an integer number (366471).

2^1221565 is an apocalyptic number.

It is an amenable number.

1221565 is a deficient number, since it is larger than the sum of its proper divisors (244319).

1221565 is an equidigital number, since it uses as much as digits as its factorization.

1221565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244318.

The product of its digits is 600, while the sum is 22.

The square root of 1221565 is about 1105.2443168820. The cubic root of 1221565 is about 106.8986433562.

Adding to 1221565 its reverse (5651221), we get a palindrome (6872786).

The spelling of 1221565 in words is "one million, two hundred twenty-one thousand, five hundred sixty-five".