1238499991 has 2 divisors, whose sum is σ = 1238499992. Its totient is φ = 1238499990.

The previous prime is 1238499989. The next prime is 1238500027. The reversal of 1238499991 is 1999948321.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1238499991 - 2¹ = 1238499989 is a prime.

Together with 1238499989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1238499901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 619249995 + 619249996.

It is an arithmetic number, because the mean of its divisors is an integer number (619249996).

Almost surely, 2^1238499991 is an apocalyptic number.

1238499991 is a deficient number, since it is larger than the sum of its proper divisors (1).

1238499991 is an equidigital number, since it uses as much as digits as its factorization.

1238499991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1259712, while the sum is 55.

The square root of 1238499991 is about 35192.3285816668. The cubic root of 1238499991 is about 1073.9036931607.

The spelling of 1238499991 in words is "one billion, two hundred thirty-eight million, four hundred ninety-nine thousand, nine hundred ninety-one".