640837 has 2 divisors, whose sum is σ = 640838. Its totient is φ = 640836.

The previous prime is 640793. The next prime is 640847. The reversal of 640837 is 738046.

640837 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 481636 + 159201 = 694^2 + 399^2 .

It is a cyclic number.

It is not a de Polignac number, because 640837 - 2¹⁹ = 116549 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320418 + 320419.

It is an arithmetic number, because the mean of its divisors is an integer number (320419).

2⁶⁴⁰⁸³⁷ is an apocalyptic number.

It is an amenable number.

640837 is a deficient number, since it is larger than the sum of its proper divisors (1).

640837 is an equidigital number, since it uses as much as digits as its factorization.

640837 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 640837 is about 800.5229540744. The cubic root of 640837 is about 86.2149391908.

The spelling of 640837 in words is "six hundred forty thousand, eight hundred thirty-seven".