136806991 has 4 divisors (see below), whose sum is σ = 138455352. Its totient is φ = 135158632.

The previous prime is 136806983. The next prime is 136807001. The reversal of 136806991 is 199608631.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199608631 = 281 ⋅710351.

It is a cyclic number.

It is not a de Polignac number, because 136806991 - 2³ = 136806983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (136806911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 824056 + ... + 824221.

It is an arithmetic number, because the mean of its divisors is an integer number (34613838).

Almost surely, 2^136806991 is an apocalyptic number.

136806991 is a deficient number, since it is larger than the sum of its proper divisors (1648361).

136806991 is an equidigital number, since it uses as much as digits as its factorization.

136806991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1648360.

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 136806991 is about 11696.4520688968. The cubic root of 136806991 is about 515.2714702856.

The spelling of 136806991 in words is "one hundred thirty-six million, eight hundred six thousand, nine hundred ninety-one".