640642 has 16 divisors (see below), whose sum is σ = 1056960. Its totient is φ = 289872.

The previous prime is 640631. The next prime is 640649. The reversal of 640642 is 246046.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 508 + ... + 1240.

It is an arithmetic number, because the mean of its divisors is an integer number (66060).

2⁶⁴⁰⁶⁴² is an apocalyptic number.

640642 is a deficient number, since it is larger than the sum of its proper divisors (416318).

640642 is a wasteful number, since it uses less digits than its factorization.

640642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777.

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 640642 is about 800.4011494245. The cubic root of 640642 is about 86.2061935354.

Adding to 640642 its reverse (246046), we get a palindrome (886688).

The spelling of 640642 in words is "six hundred forty thousand, six hundred forty-two".