642445 has 4 divisors (see below), whose sum is σ = 770940. Its totient is φ = 513952.

The previous prime is 642427. The next prime is 642457. The reversal of 642445 is 544246.

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

It can be written as a sum of positive squares in 2 ways, for example, as 119716 + 522729 = 346^2 + 723^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-642445 is a prime.

It is a congruent 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, 64240 + ... + 64249.

It is an arithmetic number, because the mean of its divisors is an integer number (192735).

2⁶⁴²⁴⁴⁵ is an apocalyptic number.

It is an amenable number.

642445 is a deficient number, since it is larger than the sum of its proper divisors (128495).

642445 is a wasteful number, since it uses less digits than its factorization.

642445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128494.

The product of its digits is 3840, while the sum is 25.

The square root of 642445 is about 801.5266683024. The cubic root of 642445 is about 86.2869896652.

The spelling of 642445 in words is "six hundred forty-two thousand, four hundred forty-five".