136991 has 2 divisors, whose sum is σ = 136992. Its totient is φ = 136990.

The previous prime is 136987. The next prime is 136993. The reversal of 136991 is 199631.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 136991 - 2² = 136987 is a prime.

Together with 136993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (136993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68495 + 68496.

It is an arithmetic number, because the mean of its divisors is an integer number (68496).

2¹³⁶⁹⁹¹ is an apocalyptic number.

136991 is a deficient number, since it is larger than the sum of its proper divisors (1).

136991 is an equidigital number, since it uses as much as digits as its factorization.

136991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1458, while the sum is 29.

The square root of 136991 is about 370.1229525442. The cubic root of 136991 is about 51.5502384680.

The spelling of 136991 in words is "one hundred thirty-six thousand, nine hundred ninety-one".