644401 has 2 divisors, whose sum is σ = 644402.
Its totient is φ = 644400.
The previous prime is 644383. The next prime is 644411. The reversal of 644401 is 104446.
Adding to 644401 its reverse (104446), we get a palindrome (748847).
It can be divided in two parts, 64 and 4401, that added together give a triangular number (4465 = T94).
644401 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 389376 + 255025 = 624^2 + 505^2
It is a cyclic number.
It is not a de Polignac number, because 644401 - 29 = 643889 is a prime.
It is an Ulam number.
644401 is a lucky number.
It is not a weakly prime, because it can be changed into another prime (644411) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322200 + 322201.
It is an arithmetic number, because the mean of its divisors is an integer number (322201).
2644401 is an apocalyptic number.
It is an amenable number.
644401 is a deficient number, since it is larger than the sum of its proper divisors (1).
644401 is an equidigital number, since it uses as much as digits as its factorization.
644401 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 384, while the sum is 19.
The square root of 644401 is about 802.7459124779.
The cubic root of 644401 is about 86.3744712672.
The spelling of 644401 in words is "six hundred forty-four thousand, four hundred one".