644958 has 12 divisors (see below), whose sum is σ = 1397448. Its totient is φ = 214980.

The previous prime is 644951. The next prime is 644977. The reversal of 644958 is 859446.

644958 is a `hidden beast` number, since 644 + 9 + 5 + 8 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644951) by changing a digit.

644958 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17898 + ... + 17933.

It is an arithmetic number, because the mean of its divisors is an integer number (116454).

2⁶⁴⁴⁹⁵⁸ is an apocalyptic number.

644958 is an abundant number, since it is smaller than the sum of its proper divisors (752490).

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

644958 is a wasteful number, since it uses less digits than its factorization.

644958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35839 (or 35836 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 644958 is about 803.0927717269. The cubic root of 644958 is about 86.3993505610.

The spelling of 644958 in words is "six hundred forty-four thousand, nine hundred fifty-eight".