1243042391 has 2 divisors, whose sum is σ = 1243042392. Its totient is φ = 1243042390.

The previous prime is 1243042379. The next prime is 1243042393. The reversal of 1243042391 is 1932403421.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1243042391 - 2¹⁰ = 1243041367 is a prime.

Together with 1243042393, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1243042393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621521195 + 621521196.

It is an arithmetic number, because the mean of its divisors is an integer number (621521196).

Almost surely, 2^1243042391 is an apocalyptic number.

1243042391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243042391 is an equidigital number, since it uses as much as digits as its factorization.

1243042391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 1243042391 is about 35256.8063074352. The cubic root of 1243042391 is about 1075.2149967677.

The spelling of 1243042391 in words is "one billion, two hundred forty-three million, forty-two thousand, three hundred ninety-one".