640822 has 24 divisors (see below), whose sum is σ = 1206576. Its totient is φ = 253008.

The previous prime is 640793. The next prime is 640837. The reversal of 640822 is 228046.

It is a junction number, because it is equal to n+sod(n) for n = 640793 and 640802.

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 11 ways as a sum of consecutive naturals, for example, 1023 + ... + 1525.

It is an arithmetic number, because the mean of its divisors is an integer number (50274).

2⁶⁴⁰⁸²² is an apocalyptic number.

640822 is a deficient number, since it is larger than the sum of its proper divisors (565754).

640822 is a wasteful number, since it uses less digits than its factorization.

640822 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532 (or 525 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 640822 is about 800.5135851439. The cubic root of 640822 is about 86.2142665111.

Adding to 640822 its reverse (228046), we get a palindrome (868868).

It can be divided in two parts, 64082 and 2, that multiplied together give a square (128164 = 358²).

The spelling of 640822 in words is "six hundred forty thousand, eight hundred twenty-two".