1231978439 has 4 divisors (see below), whose sum is σ = 1249330320. Its totient is φ = 1214626560.

The previous prime is 1231978403. The next prime is 1231978453. The reversal of 1231978439 is 9348791321.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1231978439 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1231978393 and 1231978402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231978039) 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, 8675834 + ... + 8675975.

It is an arithmetic number, because the mean of its divisors is an integer number (312332580).

Almost surely, 2^1231978439 is an apocalyptic number.

1231978439 is a deficient number, since it is larger than the sum of its proper divisors (17351881).

1231978439 is an equidigital number, since it uses as much as digits as its factorization.

1231978439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17351880.

The product of its digits is 326592, while the sum is 47.

The square root of 1231978439 is about 35099.5504102261. The cubic root of 1231978439 is about 1072.0154284067.

The spelling of 1231978439 in words is "one billion, two hundred thirty-one million, nine hundred seventy-eight thousand, four hundred thirty-nine".