649872809 has 4 divisors (see below), whose sum is σ = 670836480. Its totient is φ = 628909140.

The previous prime is 649872799. The next prime is 649872829. The reversal of 649872809 is 908278946.

649872809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 649872809 - 2⁴ = 649872793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649872829) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10481789 + ... + 10481850.

It is an arithmetic number, because the mean of its divisors is an integer number (167709120).

Almost surely, 2^649872809 is an apocalyptic number.

It is an amenable number.

649872809 is a deficient number, since it is larger than the sum of its proper divisors (20963671).

649872809 is a wasteful number, since it uses less digits than its factorization.

649872809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20963670.

The product of its (nonzero) digits is 1741824, while the sum is 53.

The square root of 649872809 is about 25492.6030251914. The cubic root of 649872809 is about 866.1826002100.

The spelling of 649872809 in words is "six hundred forty-nine million, eight hundred seventy-two thousand, eight hundred nine".