642155 has 4 divisors (see below), whose sum is σ = 770592. Its totient is φ = 513720.

The previous prime is 642151. The next prime is 642157. The reversal of 642155 is 551246.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 551246 = 2 ⋅275623.

It is not a de Polignac number, because 642155 - 2² = 642151 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 642155.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 642155.

It is not an unprimeable number, because it can be changed into a prime (642151) by changing a digit.

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, 64211 + ... + 64220.

It is an arithmetic number, because the mean of its divisors is an integer number (192648).

2⁶⁴²¹⁵⁵ is an apocalyptic number.

642155 is a deficient number, since it is larger than the sum of its proper divisors (128437).

642155 is a wasteful number, since it uses less digits than its factorization.

642155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128436.

The product of its digits is 1200, while the sum is 23.

The square root of 642155 is about 801.3457431097. The cubic root of 642155 is about 86.2740043808.

Subtracting from 642155 its reverse (551246), we obtain a palindrome (90909).

It can be divided in two parts, 642 and 155, that added together give a palindrome (797).

The spelling of 642155 in words is "six hundred forty-two thousand, one hundred fifty-five".