646739 has 4 divisors (see below), whose sum is σ = 655920. Its totient is φ = 637560.

The previous prime is 646721. The next prime is 646757. The reversal of 646739 is 937646.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (646721) and next prime (646757).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-646739 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 646699 and 646708.

It is not an unprimeable number, because it can be changed into a prime (646039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4484 + ... + 4625.

It is an arithmetic number, because the mean of its divisors is an integer number (163980).

2⁶⁴⁶⁷³⁹ is an apocalyptic number.

646739 is a deficient number, since it is larger than the sum of its proper divisors (9181).

646739 is an equidigital number, since it uses as much as digits as its factorization.

646739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9180.

The product of its digits is 27216, while the sum is 35.

The square root of 646739 is about 804.2008455604. The cubic root of 646739 is about 86.4788057711.

The spelling of 646739 in words is "six hundred forty-six thousand, seven hundred thirty-nine".