1243541221 has 4 divisors (see below), whose sum is σ = 1339198252. Its totient is φ = 1147884192.

The previous prime is 1243541213. The next prime is 1243541227. The reversal of 1243541221 is 1221453421.

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 777628996 + 465912225 = 27886^2 + 21585^2 .

It is not a de Polignac number, because 1243541221 - 2³ = 1243541213 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 (1243541227) 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, 47828496 + ... + 47828521.

It is an arithmetic number, because the mean of its divisors is an integer number (334799563).

Almost surely, 2^1243541221 is an apocalyptic number.

It is an amenable number.

1243541221 is a deficient number, since it is larger than the sum of its proper divisors (95657031).

1243541221 is an equidigital number, since it uses as much as digits as its factorization.

1243541221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95657030.

The product of its digits is 1920, while the sum is 25.

The square root of 1243541221 is about 35263.8798347544. The cubic root of 1243541221 is about 1075.3588046194.

Adding to 1243541221 its reverse (1221453421), we get a palindrome (2464994642).

The spelling of 1243541221 in words is "one billion, two hundred forty-three million, five hundred forty-one thousand, two hundred twenty-one".