1224215621 has 4 divisors (see below), whose sum is σ = 1240985772. Its totient is φ = 1207445472.

The previous prime is 1224215591. The next prime is 1224215623. The reversal of 1224215621 is 1265124221.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1265124221 = 71 ⋅17818651.

It can be written as a sum of positive squares in 2 ways, for example, as 423948100 + 800267521 = 20590^2 + 28289^2 .

It is a cyclic number.

It is not a de Polignac number, because 1224215621 - 2¹⁴ = 1224199237 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1224215623) 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, 8384966 + ... + 8385111.

It is an arithmetic number, because the mean of its divisors is an integer number (310246443).

Almost surely, 2^1224215621 is an apocalyptic number.

It is an amenable number.

1224215621 is a deficient number, since it is larger than the sum of its proper divisors (16770151).

1224215621 is an equidigital number, since it uses as much as digits as its factorization.

1224215621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16770150.

The product of its digits is 1920, while the sum is 26.

The square root of 1224215621 is about 34988.7927914068. The cubic root of 1224215621 is about 1069.7590574615.

Adding to 1224215621 its reverse (1265124221), we get a palindrome (2489339842).

The spelling of 1224215621 in words is "one billion, two hundred twenty-four million, two hundred fifteen thousand, six hundred twenty-one".