1231999 has 2 divisors, whose sum is σ = 1232000. Its totient is φ = 1231998.

The previous prime is 1231987. The next prime is 1232003. The reversal of 1231999 is 9991321.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1231999 - 2⁹ = 1231487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231099) 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, 615999 + 616000.

It is an arithmetic number, because the mean of its divisors is an integer number (616000).

2^1231999 is an apocalyptic number.

1231999 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231999 is an equidigital number, since it uses as much as digits as its factorization.

1231999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4374, while the sum is 34.

The square root of 1231999 is about 1109.9545035721. The cubic root of 1231999 is about 107.2021392144.

The spelling of 1231999 in words is "one million, two hundred thirty-one thousand, nine hundred ninety-nine".