521681685 has 48 divisors (see below), whose sum is σ = 997261056. Its totient is φ = 232025472.

The previous prime is 521681681. The next prime is 521681687. The reversal of 521681685 is 586186125.

It is not a de Polignac number, because 521681685 - 2² = 521681681 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521681681) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 17604 + ... + 36786.

It is an arithmetic number, because the mean of its divisors is an integer number (20776272).

Almost surely, 2^521681685 is an apocalyptic number.

It is an amenable number.

521681685 is a deficient number, since it is larger than the sum of its proper divisors (475579371).

521681685 is a wasteful number, since it uses less digits than its factorization.

521681685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19242 (or 19235 counting only the distinct ones).

The product of its digits is 115200, while the sum is 42.

The square root of 521681685 is about 22840.3521207533. The cubic root of 521681685 is about 805.0110899543.

The spelling of 521681685 in words is "five hundred twenty-one million, six hundred eighty-one thousand, six hundred eighty-five".