646987 has 6 divisors (see below), whose sum is σ = 711284. Its totient is φ = 588060.

The previous prime is 646981. The next prime is 646991. The reversal of 646987 is 789646.

It is not a de Polignac number, because 646987 - 2³ = 646979 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (646981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2553 + ... + 2794.

2⁶⁴⁶⁹⁸⁷ is an apocalyptic number.

646987 is a deficient number, since it is larger than the sum of its proper divisors (64297).

646987 is a wasteful number, since it uses less digits than its factorization.

646987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5369 (or 5358 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 646987 is about 804.3550211194. The cubic root of 646987 is about 86.4898581447.

It can be divided in two parts, 6469 and 87, that added together give a palindrome (6556).

The spelling of 646987 in words is "six hundred forty-six thousand, nine hundred eighty-seven".