649081 has 2 divisors, whose sum is σ = 649082. Its totient is φ = 649080.

The previous prime is 649079. The next prime is 649087. The reversal of 649081 is 180946.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 341056 + 308025 = 584^2 + 555^2 .

It is a cyclic number.

It is not a de Polignac number, because 649081 - 2¹ = 649079 is a prime.

It is a super-2 number, since 2×649081² = 842612289122, which contains 22 as substring.

Together with 649079, it forms a pair of twin primes.

649081 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (649087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324540 + 324541.

It is an arithmetic number, because the mean of its divisors is an integer number (324541).

2⁶⁴⁹⁰⁸¹ is an apocalyptic number.

It is an amenable number.

649081 is a deficient number, since it is larger than the sum of its proper divisors (1).

649081 is an equidigital number, since it uses as much as digits as its factorization.

649081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 649081 is about 805.6556336302. The cubic root of 649081 is about 86.5830669850.

The spelling of 649081 in words is "six hundred forty-nine thousand, eighty-one".