649891 has 12 divisors (see below), whose sum is σ = 737352. Its totient is φ = 572000.

The previous prime is 649879. The next prime is 649897. The reversal of 649891 is 198946.

It is not a de Polignac number, because 649891 - 2⁹ = 649379 is a prime.

It is a nialpdrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 649891.

It is not an unprimeable number, because it can be changed into a prime (649897) 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 11 ways as a sum of consecutive naturals, for example, 4896 + ... + 5026.

It is an arithmetic number, because the mean of its divisors is an integer number (61446).

2⁶⁴⁹⁸⁹¹ is an apocalyptic number.

649891 is a deficient number, since it is larger than the sum of its proper divisors (87461).

649891 is a wasteful number, since it uses less digits than its factorization.

649891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 183 counting only the distinct ones).

The product of its digits is 15552, while the sum is 37.

The square root of 649891 is about 806.1581730653. The cubic root of 649891 is about 86.6190682089.

It can be divided in two parts, 649 and 891, that added together give a triangular number (1540 = T₅₅).

The spelling of 649891 in words is "six hundred forty-nine thousand, eight hundred ninety-one".