1243215109 has 4 divisors (see below), whose sum is σ = 1243287616. Its totient is φ = 1243142604.

The previous prime is 1243215107. The next prime is 1243215121. The reversal of 1243215109 is 9015123421.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 9015123421 = 1801 ⋅5005621.

It is a cyclic number.

It is not a de Polignac number, because 1243215109 - 2¹ = 1243215107 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 (1243215107) 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, 5482 + ... + 50164.

It is an arithmetic number, because the mean of its divisors is an integer number (310821904).

Almost surely, 2^1243215109 is an apocalyptic number.

It is an amenable number.

1243215109 is a deficient number, since it is larger than the sum of its proper divisors (72507).

1243215109 is an equidigital number, since it uses as much as digits as its factorization.

1243215109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72506.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 1243215109 is about 35259.2556501126. The cubic root of 1243215109 is about 1075.2647940458.

The spelling of 1243215109 in words is "one billion, two hundred forty-three million, two hundred fifteen thousand, one hundred nine".