649728891 has 16 divisors (see below), whose sum is σ = 1100070400. Its totient is φ = 371273544.

The previous prime is 649728889. The next prime is 649728901. The reversal of 649728891 is 198827946.

It is not a de Polignac number, because 649728891 - 2¹ = 649728889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649728851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1718671 + ... + 1719048.

It is an arithmetic number, because the mean of its divisors is an integer number (68754400).

Almost surely, 2^649728891 is an apocalyptic number.

649728891 is a deficient number, since it is larger than the sum of its proper divisors (450341509).

649728891 is a wasteful number, since it uses less digits than its factorization.

649728891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3437735 (or 3437729 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 54.

The square root of 649728891 is about 25489.7801285143. The cubic root of 649728891 is about 866.1186551482.

The spelling of 649728891 in words is "six hundred forty-nine million, seven hundred twenty-eight thousand, eight hundred ninety-one".