856778149 has 2 divisors, whose sum is σ = 856778150. Its totient is φ = 856778148.

The previous prime is 856778137. The next prime is 856778159. The reversal of 856778149 is 941877658.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 466992100 + 389786049 = 21610^2 + 19743^2 .

It is a cyclic number.

It is not a de Polignac number, because 856778149 - 2⁹ = 856777637 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 856778149.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856778159) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428389074 + 428389075.

It is an arithmetic number, because the mean of its divisors is an integer number (428389075).

Almost surely, 2^856778149 is an apocalyptic number.

It is an amenable number.

856778149 is a deficient number, since it is larger than the sum of its proper divisors (1).

856778149 is an equidigital number, since it uses as much as digits as its factorization.

856778149 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3386880, while the sum is 55.

The square root of 856778149 is about 29270.7729484549. The cubic root of 856778149 is about 949.7795052445.

The spelling of 856778149 in words is "eight hundred fifty-six million, seven hundred seventy-eight thousand, one hundred forty-nine".