644650 has 12 divisors (see below), whose sum is σ = 1199142. Its totient is φ = 257840.

The previous prime is 644647. The next prime is 644653. The reversal of 644650 is 56446.

It is a happy number.

644650 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (644647) and next prime (644653).

It can be written as a sum of positive squares in 3 ways, for example, as 505521 + 139129 = 711^2 + 373^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (644653) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6397 + ... + 6496.

2⁶⁴⁴⁶⁵⁰ is an apocalyptic number.

644650 is a deficient number, since it is larger than the sum of its proper divisors (554492).

644650 is a wasteful number, since it uses less digits than its factorization.

644650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12905 (or 12900 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 25.

The square root of 644650 is about 802.9009901601. The cubic root of 644650 is about 86.3855950207.

The spelling of 644650 in words is "six hundred forty-four thousand, six hundred fifty".