1243215121 has 2 divisors, whose sum is σ = 1243215122. Its totient is φ = 1243215120.

The previous prime is 1243215107. The next prime is 1243215139. The reversal of 1243215121 is 1215123421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 996096721 + 247118400 = 31561^2 + 15720^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243215121 - 2¹⁹ = 1242690833 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1243215092 and 1243215101.

It is not a weakly prime, because it can be changed into another prime (1243218121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621607560 + 621607561.

It is an arithmetic number, because the mean of its divisors is an integer number (621607561).

Almost surely, 2^1243215121 is an apocalyptic number.

It is an amenable number.

1243215121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243215121 is an equidigital number, since it uses as much as digits as its factorization.

1243215121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 22.

The square root of 1243215121 is about 35259.2558202807. The cubic root of 1243215121 is about 1075.2647975055.

Adding to 1243215121 its reverse (1215123421), we get a palindrome (2458338542).

The spelling of 1243215121 in words is "one billion, two hundred forty-three million, two hundred fifteen thousand, one hundred twenty-one".