684385781 has 8 divisors (see below), whose sum is σ = 714798240. Its totient is φ = 654600528.

The previous prime is 684385777. The next prime is 684385783. The reversal of 684385781 is 187583486.

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 684385781 - 2² = 684385777 is a prime.

It is a super-2 number, since 2×684385781² = 936767794469959922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (684385783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154571 + ... + 158936.

It is an arithmetic number, because the mean of its divisors is an integer number (89349780).

Almost surely, 2^684385781 is an apocalyptic number.

It is an amenable number.

684385781 is a deficient number, since it is larger than the sum of its proper divisors (30412459).

684385781 is a wasteful number, since it uses less digits than its factorization.

684385781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313603.

The product of its digits is 1290240, while the sum is 50.

The square root of 684385781 is about 26160.7679742014. The cubic root of 684385781 is about 881.2524268263.

The spelling of 684385781 in words is "six hundred eighty-four million, three hundred eighty-five thousand, seven hundred eighty-one".