1243257121 has 4 divisors (see below), whose sum is σ = 1243365700. Its totient is φ = 1243148544.

The previous prime is 1243257089. The next prime is 1243257131. The reversal of 1243257121 is 1217523421.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 82901025 + 1160356096 = 9105^2 + 34064^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243257121 - 2⁵ = 1243257089 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1243257121.

It is not an unprimeable number, because it can be changed into a prime (1243257131) 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, 34776 + ... + 60793.

It is an arithmetic number, because the mean of its divisors is an integer number (310841425).

Almost surely, 2^1243257121 is an apocalyptic number.

It is an amenable number.

1243257121 is a deficient number, since it is larger than the sum of its proper divisors (108579).

1243257121 is an equidigital number, since it uses as much as digits as its factorization.

1243257121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108578.

The product of its digits is 3360, while the sum is 28.

The square root of 1243257121 is about 35259.8514035439. The cubic root of 1243257121 is about 1075.2769060597.

The spelling of 1243257121 in words is "one billion, two hundred forty-three million, two hundred fifty-seven thousand, one hundred twenty-one".