640742 has 8 divisors (see below), whose sum is σ = 966000. Its totient is φ = 318744.

The previous prime is 640741. The next prime is 640771. The reversal of 640742 is 247046.

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

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640742.

It is not an unprimeable number, because it can be changed into a prime (640741) 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, 242 + ... + 1157.

It is an arithmetic number, because the mean of its divisors is an integer number (120750).

2⁶⁴⁰⁷⁴² is an apocalyptic number.

640742 is a deficient number, since it is larger than the sum of its proper divisors (325258).

640742 is a wasteful number, since it uses less digits than its factorization.

640742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1630.

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 640742 is about 800.4636156628. The cubic root of 640742 is about 86.2106787085.

Adding to 640742 its reverse (247046), we get a palindrome (887788).

The spelling of 640742 in words is "six hundred forty thousand, seven hundred forty-two".