646731 has 16 divisors (see below), whose sum is σ = 1015200. Its totient is φ = 405504.

The previous prime is 646721. The next prime is 646757. The reversal of 646731 is 137646.

It is not a de Polignac number, because 646731 - 2¹⁹ = 122443 is a prime.

It is a super-2 number, since 2×646731² = 836521972722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 646695 and 646704.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 646731.

It is not an unprimeable number, because it can be changed into a prime (646721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246 + ... + 1163.

It is an arithmetic number, because the mean of its divisors is an integer number (63450).

2⁶⁴⁶⁷³¹ is an apocalyptic number.

646731 is a deficient number, since it is larger than the sum of its proper divisors (368469).

646731 is a wasteful number, since it uses less digits than its factorization.

646731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1435 (or 1429 counting only the distinct ones).

The product of its digits is 3024, while the sum is 27.

The square root of 646731 is about 804.1958716631. The cubic root of 646731 is about 86.4784491959.

The spelling of 646731 in words is "six hundred forty-six thousand, seven hundred thirty-one".