863844991 has 2 divisors, whose sum is σ = 863844992. Its totient is φ = 863844990.

The previous prime is 863844941. The next prime is 863844997. The reversal of 863844991 is 199448368.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 863844991 - 2⁹ = 863844479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (863844997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 431922495 + 431922496.

It is an arithmetic number, because the mean of its divisors is an integer number (431922496).

Almost surely, 2^863844991 is an apocalyptic number.

863844991 is a deficient number, since it is larger than the sum of its proper divisors (1).

863844991 is an equidigital number, since it uses as much as digits as its factorization.

863844991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1492992, while the sum is 52.

The square root of 863844991 is about 29391.2400384877. The cubic root of 863844991 is about 952.3836691054.

The spelling of 863844991 in words is "eight hundred sixty-three million, eight hundred forty-four thousand, nine hundred ninety-one".