646637 has 2 divisors, whose sum is σ = 646638. Its totient is φ = 646636.

The previous prime is 646631. The next prime is 646643. The reversal of 646637 is 736646.

It is a balanced prime because it is at equal distance from previous prime (646631) and next prime (646643).

It can be written as a sum of positive squares in only one way, i.e., 491401 + 155236 = 701^2 + 394^2 .

It is a cyclic number.

It is not a de Polignac number, because 646637 - 2⁶ = 646573 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 (646631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323318 + 323319.

It is an arithmetic number, because the mean of its divisors is an integer number (323319).

2⁶⁴⁶⁶³⁷ is an apocalyptic number.

It is an amenable number.

646637 is a deficient number, since it is larger than the sum of its proper divisors (1).

646637 is an equidigital number, since it uses as much as digits as its factorization.

646637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 32.

The square root of 646637 is about 804.1374260660. The cubic root of 646637 is about 86.4742592168.

Subtracting 646637 from its reverse (736646), we obtain a palindrome (90009).

The spelling of 646637 in words is "six hundred forty-six thousand, six hundred thirty-seven".