644394 has 16 divisors (see below), whose sum is σ = 1297440. Its totient is φ = 213360.

The previous prime is 644383. The next prime is 644401. The reversal of 644394 is 493446.

644394 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-5 number, since 5×644394⁵ (a number of 30 digits) contains 55555 as substring.

It is a d-powerful number, because it can be written as 6⁶ + 4² + 3¹² + 4² + 9³ + 4⁸ .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1012 + ... + 1520.

It is an arithmetic number, because the mean of its divisors is an integer number (81090).

2⁶⁴⁴³⁹⁴ is an apocalyptic number.

644394 is an abundant number, since it is smaller than the sum of its proper divisors (653046).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644394 is a wasteful number, since it uses less digits than its factorization.

644394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725.

The product of its digits is 10368, while the sum is 30.

The square root of 644394 is about 802.7415524314. The cubic root of 644394 is about 86.3741585098.

The spelling of 644394 in words is "six hundred forty-four thousand, three hundred ninety-four".