1243917221 has 4 divisors (see below), whose sum is σ = 1254925452. Its totient is φ = 1232908992.

The previous prime is 1243917187. The next prime is 1243917223. The reversal of 1243917221 is 1227193421.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1227193421 = 16139 ⋅76039.

It can be written as a sum of positive squares in 2 ways, for example, as 95452900 + 1148464321 = 9770^2 + 33889^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243917221 - 2²² = 1239722917 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 (1243917223) 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, 5503946 + ... + 5504171.

It is an arithmetic number, because the mean of its divisors is an integer number (313731363).

Almost surely, 2^1243917221 is an apocalyptic number.

It is an amenable number.

1243917221 is a deficient number, since it is larger than the sum of its proper divisors (11008231).

1243917221 is a wasteful number, since it uses less digits than its factorization.

1243917221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11008230.

The product of its digits is 6048, while the sum is 32.

The square root of 1243917221 is about 35269.2106659619. The cubic root of 1243917221 is about 1075.4671763561.

The spelling of 1243917221 in words is "one billion, two hundred forty-three million, nine hundred seventeen thousand, two hundred twenty-one".