642191 has 8 divisors (see below), whose sum is σ = 710400. Its totient is φ = 575640.

The previous prime is 642163. The next prime is 642197. The reversal of 642191 is 191246.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 642191 - 2¹⁰ = 641167 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642197) 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 7 ways as a sum of consecutive naturals, for example, 500 + ... + 1238.

It is an arithmetic number, because the mean of its divisors is an integer number (88800).

2⁶⁴²¹⁹¹ is an apocalyptic number.

642191 is a deficient number, since it is larger than the sum of its proper divisors (68209).

642191 is a wasteful number, since it uses less digits than its factorization.

642191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 829.

The product of its digits is 432, while the sum is 23.

The square root of 642191 is about 801.3682050094. The cubic root of 642191 is about 86.2756165596.

The spelling of 642191 in words is "six hundred forty-two thousand, one hundred ninety-one".