865638131 has 2 divisors, whose sum is σ = 865638132. Its totient is φ = 865638130.

The previous prime is 865638127. The next prime is 865638149. The reversal of 865638131 is 131836568.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 865638131 - 2² = 865638127 is a prime.

It is a super-2 number, since 2×865638131² = 1498658747682346322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (865638101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432819065 + 432819066.

It is an arithmetic number, because the mean of its divisors is an integer number (432819066).

Almost surely, 2^865638131 is an apocalyptic number.

865638131 is a deficient number, since it is larger than the sum of its proper divisors (1).

865638131 is an equidigital number, since it uses as much as digits as its factorization.

865638131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 41.

The square root of 865638131 is about 29421.7288920961. The cubic root of 865638131 is about 953.0421888615.

The spelling of 865638131 in words is "eight hundred sixty-five million, six hundred thirty-eight thousand, one hundred thirty-one".