865638149 has 2 divisors, whose sum is σ = 865638150. Its totient is φ = 865638148.

The previous prime is 865638131. The next prime is 865638187. The reversal of 865638149 is 941836568.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 604815649 + 260822500 = 24593^2 + 16150^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-865638149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 865638097 and 865638106.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (865638049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432819074 + 432819075.

It is an arithmetic number, because the mean of its divisors is an integer number (432819075).

Almost surely, 2^865638149 is an apocalyptic number.

It is an amenable number.

865638149 is a deficient number, since it is larger than the sum of its proper divisors (1).

865638149 is an equidigital number, since it uses as much as digits as its factorization.

865638149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 50.

The square root of 865638149 is about 29421.7291979924. The cubic root of 865638149 is about 953.0421954673.

The spelling of 865638149 in words is "eight hundred sixty-five million, six hundred thirty-eight thousand, one hundred forty-nine".