856649 has 2 divisors, whose sum is σ = 856650. Its totient is φ = 856648.

The previous prime is 856637. The next prime is 856693. The reversal of 856649 is 946658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 855625 + 1024 = 925^2 + 32^2 .

It is a cyclic number.

It is not a de Polignac number, because 856649 - 2⁸ = 856393 is a prime.

It is a Chen prime.

It is a nialpdrome in base 8.

It is not a weakly prime, because it can be changed into another prime (856699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428324 + 428325.

It is an arithmetic number, because the mean of its divisors is an integer number (428325).

2⁸⁵⁶⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

856649 is a deficient number, since it is larger than the sum of its proper divisors (1).

856649 is an equidigital number, since it uses as much as digits as its factorization.

856649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 38.

The square root of 856649 is about 925.5533480032. The cubic root of 856649 is about 94.9731780235.

Subtracting 856649 from its reverse (946658), we obtain a palindrome (90009).

The spelling of 856649 in words is "eight hundred fifty-six thousand, six hundred forty-nine".