1221144521 has 4 divisors (see below), whose sum is σ = 1224284100. Its totient is φ = 1218004944.

The previous prime is 1221144503. The next prime is 1221144523. The reversal of 1221144521 is 1254411221.

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 825930121 + 395214400 = 28739^2 + 19880^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221144521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221144523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1569206 + ... + 1569983.

It is an arithmetic number, because the mean of its divisors is an integer number (306071025).

Almost surely, 2^1221144521 is an apocalyptic number.

It is an amenable number.

1221144521 is a deficient number, since it is larger than the sum of its proper divisors (3139579).

1221144521 is an equidigital number, since it uses as much as digits as its factorization.

1221144521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3139578.

The product of its digits is 640, while the sum is 23.

The square root of 1221144521 is about 34944.8783228673. The cubic root of 1221144521 is about 1068.8637663466.

Adding to 1221144521 its reverse (1254411221), we get a palindrome (2475555742).

The spelling of 1221144521 in words is "one billion, two hundred twenty-one million, one hundred forty-four thousand, five hundred twenty-one".