684655661 has 4 divisors (see below), whose sum is σ = 684913152. Its totient is φ = 684398172.

The previous prime is 684655613. The next prime is 684655663. The reversal of 684655661 is 166556486.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 684655661 - 2²² = 680461357 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 (684655663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124715 + ... + 130088.

It is an arithmetic number, because the mean of its divisors is an integer number (171228288).

Almost surely, 2^684655661 is an apocalyptic number.

It is an amenable number.

684655661 is a deficient number, since it is larger than the sum of its proper divisors (257491).

684655661 is a wasteful number, since it uses less digits than its factorization.

684655661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257490.

The product of its digits is 1036800, while the sum is 47.

The square root of 684655661 is about 26165.9255712463. The cubic root of 684655661 is about 881.3682490016.

The spelling of 684655661 in words is "six hundred eighty-four million, six hundred fifty-five thousand, six hundred sixty-one".