644749989 has 8 divisors (see below), whose sum is σ = 925794912. Its totient is φ = 396769200.

The previous prime is 644749967. The next prime is 644750003. The reversal of 644749989 is 989947446.

It is a happy number.

644749989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644749989 - 2⁸ = 644749733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644749949) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8265987 + ... + 8266064.

It is an arithmetic number, because the mean of its divisors is an integer number (115724364).

Almost surely, 2^644749989 is an apocalyptic number.

It is an amenable number.

644749989 is a deficient number, since it is larger than the sum of its proper divisors (281044923).

644749989 is a wasteful number, since it uses less digits than its factorization.

644749989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16532067.

The product of its digits is 15676416, while the sum is 60.

The square root of 644749989 is about 25391.9276345850. The cubic root of 644749989 is about 863.9006109418.

The spelling of 644749989 in words is "six hundred forty-four million, seven hundred forty-nine thousand, nine hundred eighty-nine".