136781321 has 4 divisors (see below), whose sum is σ = 136834452. Its totient is φ = 136728192.

The previous prime is 136781297. The next prime is 136781329. The reversal of 136781321 is 123187631.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 100721296 + 36060025 = 10036^2 + 6005^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-136781321 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (136781329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22496 + ... + 27921.

It is an arithmetic number, because the mean of its divisors is an integer number (34208613).

Almost surely, 2^136781321 is an apocalyptic number.

It is an amenable number.

136781321 is a deficient number, since it is larger than the sum of its proper divisors (53131).

136781321 is an equidigital number, since it uses as much as digits as its factorization.

136781321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53130.

The product of its digits is 6048, while the sum is 32.

The square root of 136781321 is about 11695.3546761097. The cubic root of 136781321 is about 515.2392403391.

The spelling of 136781321 in words is "one hundred thirty-six million, seven hundred eighty-one thousand, three hundred twenty-one".