644897 has 8 divisors (see below), whose sum is σ = 734400. Its totient is φ = 560560.

The previous prime is 644881. The next prime is 644899. The reversal of 644897 is 798446.

It is a happy number.

644897 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 644897 - 2⁴ = 644881 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644897.

It is not an unprimeable number, because it can be changed into a prime (644899) 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, 1022 + ... + 1527.

It is an arithmetic number, because the mean of its divisors is an integer number (91800).

2⁶⁴⁴⁸⁹⁷ is an apocalyptic number.

It is an amenable number.

644897 is a deficient number, since it is larger than the sum of its proper divisors (89503).

644897 is a wasteful number, since it uses less digits than its factorization.

644897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2583.

The product of its digits is 48384, while the sum is 38.

The square root of 644897 is about 803.0547926512. The cubic root of 644897 is about 86.3966265973.

The spelling of 644897 in words is "six hundred forty-four thousand, eight hundred ninety-seven".