646986 has 16 divisors (see below), whose sum is σ = 1370304. Its totient is φ = 202944.

The previous prime is 646981. The next prime is 646991. The reversal of 646986 is 689646.

It is an interprime number because it is at equal distance from previous prime (646981) and next prime (646991).

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.

646986 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3070 + ... + 3273.

It is an arithmetic number, because the mean of its divisors is an integer number (85644).

2⁶⁴⁶⁹⁸⁶ is an apocalyptic number.

646986 is an abundant number, since it is smaller than the sum of its proper divisors (723318).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646986 is a wasteful number, since it uses less digits than its factorization.

646986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6365.

The product of its digits is 62208, while the sum is 39.

The square root of 646986 is about 804.3543995031. The cubic root of 646986 is about 86.4898135844.

It can be divided in two parts, 6469 and 86, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 646986 in words is "six hundred forty-six thousand, nine hundred eighty-six".