649991 has 2 divisors, whose sum is σ = 649992. Its totient is φ = 649990.

The previous prime is 649981. The next prime is 650011. The reversal of 649991 is 199946.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-649991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (649921) 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 as a sum of consecutive naturals, namely, 324995 + 324996.

It is an arithmetic number, because the mean of its divisors is an integer number (324996).

2⁶⁴⁹⁹⁹¹ is an apocalyptic number.

649991 is a deficient number, since it is larger than the sum of its proper divisors (1).

649991 is an equidigital number, since it uses as much as digits as its factorization.

649991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 38.

The square root of 649991 is about 806.2201932475. The cubic root of 649991 is about 86.6235107296.

The spelling of 649991 in words is "six hundred forty-nine thousand, nine hundred ninety-one".