644351 has 8 divisors (see below), whose sum is σ = 706320. Its totient is φ = 585088.

The previous prime is 644341. The next prime is 644353. The reversal of 644351 is 153446.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644351 is a prime.

It is a super-2 number, since 2×644351² = 830376422402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644353) 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, 161 + ... + 1146.

It is an arithmetic number, because the mean of its divisors is an integer number (88290).

2⁶⁴⁴³⁵¹ is an apocalyptic number.

644351 is a deficient number, since it is larger than the sum of its proper divisors (61969).

644351 is a wasteful number, since it uses less digits than its factorization.

644351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353.

The product of its digits is 1440, while the sum is 23.

The square root of 644351 is about 802.7147687691. The cubic root of 644351 is about 86.3722372363.

Adding to 644351 its reverse (153446), we get a palindrome (797797).

The spelling of 644351 in words is "six hundred forty-four thousand, three hundred fifty-one".