136991991 has 8 divisors (see below), whose sum is σ = 183070080. Its totient is φ = 91120952.

The previous prime is 136991971. The next prime is 136992013. The reversal of 136991991 is 199199631.

136991991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 136991991 - 2⁶ = 136991927 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 136991991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (136991951) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50211 + ... + 52868.

It is an arithmetic number, because the mean of its divisors is an integer number (22883760).

Almost surely, 2^136991991 is an apocalyptic number.

136991991 is a deficient number, since it is larger than the sum of its proper divisors (46078089).

136991991 is a wasteful number, since it uses less digits than its factorization.

136991991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103525.

The product of its digits is 118098, while the sum is 48.

The square root of 136991991 is about 11704.3577781953. The cubic root of 136991991 is about 515.5036277338.

The spelling of 136991991 in words is "one hundred thirty-six million, nine hundred ninety-one thousand, nine hundred ninety-one".