642755 has 4 divisors (see below), whose sum is σ = 771312. Its totient is φ = 514200.

The previous prime is 642739. The next prime is 642769. The reversal of 642755 is 557246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 557246 = 2 ⋅278623.

It is not a de Polignac number, because 642755 - 2⁴ = 642739 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64271 + ... + 64280.

It is an arithmetic number, because the mean of its divisors is an integer number (192828).

2⁶⁴²⁷⁵⁵ is an apocalyptic number.

642755 is a deficient number, since it is larger than the sum of its proper divisors (128557).

642755 is a wasteful number, since it uses less digits than its factorization.

642755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128556.

The product of its digits is 8400, while the sum is 29.

The square root of 642755 is about 801.7200259442. The cubic root of 642755 is about 86.3008661659.

The spelling of 642755 in words is "six hundred forty-two thousand, seven hundred fifty-five".