664138 has 4 divisors (see below), whose sum is σ = 996210. Its totient is φ = 332068.

The previous prime is 664133. The next prime is 664141. The reversal of 664138 is 831466.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 375769 + 288369 = 613^2 + 537^2 .

It is not an unprimeable number, because it can be changed into a prime (664133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166033 + ... + 166036.

2⁶⁶⁴¹³⁸ is an apocalyptic number.

664138 is a deficient number, since it is larger than the sum of its proper divisors (332072).

664138 is a wasteful number, since it uses less digits than its factorization.

664138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 332071.

The product of its digits is 3456, while the sum is 28.

The square root of 664138 is about 814.9466240190. The cubic root of 664138 is about 87.2474568433.

The spelling of 664138 in words is "six hundred sixty-four thousand, one hundred thirty-eight".