1243779913 has 4 divisors (see below), whose sum is σ = 1260818068. Its totient is φ = 1226741760.

The previous prime is 1243779907. The next prime is 1243779931. The reversal of 1243779913 is 3199773421.

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 751472569 + 492307344 = 27413^2 + 22188^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243779913 - 2¹³ = 1243771721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1243771913) 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, 8518968 + ... + 8519113.

It is an arithmetic number, because the mean of its divisors is an integer number (315204517).

Almost surely, 2^1243779913 is an apocalyptic number.

It is an amenable number.

1243779913 is a deficient number, since it is larger than the sum of its proper divisors (17038155).

1243779913 is an equidigital number, since it uses as much as digits as its factorization.

1243779913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17038154.

The product of its digits is 285768, while the sum is 46.

The square root of 1243779913 is about 35267.2640418845. The cubic root of 1243779913 is about 1075.4276036047.

The spelling of 1243779913 in words is "one billion, two hundred forty-three million, seven hundred seventy-nine thousand, nine hundred thirteen".