684631 has 4 divisors (see below), whose sum is σ = 686952. Its totient is φ = 682312.

The previous prime is 684617. The next prime is 684637. The reversal of 684631 is 136486.

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

It is a cyclic number.

It is not a de Polignac number, because 684631 - 2⁵ = 684599 is a prime.

It is a super-2 number, since 2×684631² = 937439212322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 684631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 640 + ... + 1333.

It is an arithmetic number, because the mean of its divisors is an integer number (171738).

2⁶⁸⁴⁶³¹ is an apocalyptic number.

684631 is a deficient number, since it is larger than the sum of its proper divisors (2321).

684631 is a wasteful number, since it uses less digits than its factorization.

684631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2320.

The product of its digits is 3456, while the sum is 28.

The square root of 684631 is about 827.4243167807. The cubic root of 684631 is about 88.1357666707.

It can be divided in two parts, 6846 and 31, that multiplied together give a triangular number (212226 = T₆₅₁).

The spelling of 684631 in words is "six hundred eighty-four thousand, six hundred thirty-one".