51685583835581 has 4 divisors (see below), whose sum is σ = 52266320732700. Its totient is φ = 51104846938464.

The previous prime is 51685583835553. The next prime is 51685583835647. The reversal of 51685583835581 is 18553838558615.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 36298275288025 + 15387308547556 = 6024805^2 + 3922666^2 .

It is a cyclic number.

It is not a de Polignac number, because 51685583835581 - 2²² = 51685579641277 is a prime.

It is a super-2 number, since 2×51685583835581² (a number of 28 digits) 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 (51685583835541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 290368448426 + ... + 290368448603.

It is an arithmetic number, because the mean of its divisors is an integer number (13066580183175).

Almost surely, 2^{51685583835581} is an apocalyptic number.

It is an amenable number.

51685583835581 is a deficient number, since it is larger than the sum of its proper divisors (580736897119).

51685583835581 is an equidigital number, since it uses as much as digits as its factorization.

51685583835581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580736897118.

The product of its digits is 691200000, while the sum is 71.

The spelling of 51685583835581 in words is "fifty-one trillion, six hundred eighty-five billion, five hundred eighty-three million, eight hundred thirty-five thousand, five hundred eighty-one".