840649 has 4 divisors (see below), whose sum is σ = 853264. Its totient is φ = 828036.

The previous prime is 840643. The next prime is 840661. The reversal of 840649 is 946048.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 840649 - 2⁹ = 840137 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 840649.

It is not an unprimeable number, because it can be changed into a prime (840643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6207 + ... + 6340.

It is an arithmetic number, because the mean of its divisors is an integer number (213316).

2⁸⁴⁰⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

840649 is a deficient number, since it is larger than the sum of its proper divisors (12615).

840649 is a wasteful number, since it uses less digits than its factorization.

840649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12614.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 840649 is about 916.8691291564. The cubic root of 840649 is about 94.3781732190.

The spelling of 840649 in words is "eight hundred forty thousand, six hundred forty-nine".