649889809 has 4 divisors (see below), whose sum is σ = 651281904. Its totient is φ = 648497716.

The previous prime is 649889803. The next prime is 649889833. The reversal of 649889809 is 908988946.

It is a happy number.

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 649889809 - 2¹⁵ = 649857041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649889803) 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, 695347 + ... + 696280.

It is an arithmetic number, because the mean of its divisors is an integer number (162820476).

Almost surely, 2^649889809 is an apocalyptic number.

It is an amenable number.

649889809 is a deficient number, since it is larger than the sum of its proper divisors (1392095).

649889809 is a wasteful number, since it uses less digits than its factorization.

649889809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1392094.

The product of its (nonzero) digits is 8957952, while the sum is 61.

The square root of 649889809 is about 25492.9364530648. The cubic root of 649889809 is about 866.1901529575.

The spelling of 649889809 in words is "six hundred forty-nine million, eight hundred eighty-nine thousand, eight hundred nine".