643138 has 4 divisors (see below), whose sum is σ = 964710. Its totient is φ = 321568.

The previous prime is 643129. The next prime is 643183. The reversal of 643138 is 831346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 831346 = 2 ⋅415673.

It can be written as a sum of positive squares in only one way, i.e., 522729 + 120409 = 723^2 + 347^2 .

It is an unprimeable number.

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, 160783 + ... + 160786.

2⁶⁴³¹³⁸ is an apocalyptic number.

643138 is a deficient number, since it is larger than the sum of its proper divisors (321572).

643138 is a wasteful number, since it uses less digits than its factorization.

643138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321571.

The product of its digits is 1728, while the sum is 25.

The square root of 643138 is about 801.9588518122. The cubic root of 643138 is about 86.3180041987.

The spelling of 643138 in words is "six hundred forty-three thousand, one hundred thirty-eight".