684685021 has 8 divisors (see below), whose sum is σ = 703123200. Its totient is φ = 666491280.

The previous prime is 684684997. The next prime is 684685061. The reversal of 684685021 is 120586486.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 684685021 - 2⁵ = 684684989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684685061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55426 + ... + 66643.

It is an arithmetic number, because the mean of its divisors is an integer number (87890400).

Almost surely, 2^684685021 is an apocalyptic number.

It is an amenable number.

684685021 is a deficient number, since it is larger than the sum of its proper divisors (18438179).

684685021 is a wasteful number, since it uses less digits than its factorization.

684685021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122219.

The product of its (nonzero) digits is 92160, while the sum is 40.

The square root of 684685021 is about 26166.4866002297. The cubic root of 684685021 is about 881.3808473550.

The spelling of 684685021 in words is "six hundred eighty-four million, six hundred eighty-five thousand, twenty-one".