684505661 has 8 divisors (see below), whose sum is σ = 803435520. Its totient is φ = 570861648.

The previous prime is 684505649. The next prime is 684505667. The reversal of 684505661 is 166505486.

It is a happy number.

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

It is not a de Polignac number, because 684505661 - 2¹⁰ = 684504637 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 (684505667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1321181 + ... + 1321698.

It is an arithmetic number, because the mean of its divisors is an integer number (100429440).

Almost surely, 2^684505661 is an apocalyptic number.

It is an amenable number.

684505661 is a deficient number, since it is larger than the sum of its proper divisors (118929859).

684505661 is a wasteful number, since it uses less digits than its factorization.

684505661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2642923.

The product of its (nonzero) digits is 172800, while the sum is 41.

The square root of 684505661 is about 26163.0590910161. The cubic root of 684505661 is about 881.3038784959.

The spelling of 684505661 in words is "six hundred eighty-four million, five hundred five thousand, six hundred sixty-one".