204312391 has 2 divisors, whose sum is σ = 204312392. Its totient is φ = 204312390.

The previous prime is 204312379. The next prime is 204312463. The reversal of 204312391 is 193213402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 204312391 - 2⁵ = 204312359 is a prime.

It is a super-2 number, since 2×204312391² = 83487106232273762, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (204312331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102156195 + 102156196.

It is an arithmetic number, because the mean of its divisors is an integer number (102156196).

Almost surely, 2^204312391 is an apocalyptic number.

204312391 is a deficient number, since it is larger than the sum of its proper divisors (1).

204312391 is an equidigital number, since it uses as much as digits as its factorization.

204312391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 204312391 is about 14293.7885460783. The cubic root of 204312391 is about 588.9768641412.

Adding to 204312391 its reverse (193213402), we get a palindrome (397525793).

It can be divided in two parts, 20431 and 2391, that added together give a palindrome (22822).

The spelling of 204312391 in words is "two hundred four million, three hundred twelve thousand, three hundred ninety-one".