646631 has 2 divisors, whose sum is σ = 646632. Its totient is φ = 646630.

The previous prime is 646619. The next prime is 646637. The reversal of 646631 is 136646.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 646631 - 2¹⁴ = 630247 is a prime.

It is a super-2 number, since 2×646631² = 836263300322, which contains 22 as substring.

It is a Chen prime.

It is equal to p₅₂₅₆₈ and since 646631 and 52568 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 646631.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323315 + 323316.

It is an arithmetic number, because the mean of its divisors is an integer number (323316).

2⁶⁴⁶⁶³¹ is an apocalyptic number.

646631 is a deficient number, since it is larger than the sum of its proper divisors (1).

646631 is an equidigital number, since it uses as much as digits as its factorization.

646631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 26.

The square root of 646631 is about 804.1336953517. The cubic root of 646631 is about 86.4739917576.

The spelling of 646631 in words is "six hundred forty-six thousand, six hundred thirty-one".