135999991 has 2 divisors, whose sum is σ = 135999992. Its totient is φ = 135999990.

The previous prime is 135999979. The next prime is 136000021. The reversal of 135999991 is 199999531.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 135999991 - 2¹⁷ = 135868919 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (135999691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 67999995 + 67999996.

It is an arithmetic number, because the mean of its divisors is an integer number (67999996).

Almost surely, 2^135999991 is an apocalyptic number.

135999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

135999991 is an equidigital number, since it uses as much as digits as its factorization.

135999991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 885735, while the sum is 55.

The square root of 135999991 is about 11661.9034038188. The cubic root of 135999991 is about 514.2563067878.

The spelling of 135999991 in words is "one hundred thirty-five million, nine hundred ninety-nine thousand, nine hundred ninety-one".