51691812587 has 4 divisors (see below), whose sum is σ = 52272619560. Its totient is φ = 51111005616.

The previous prime is 51691812577. The next prime is 51691812589. The reversal of 51691812587 is 78521819615.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51691812587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51691812589) 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 3 ways as a sum of consecutive naturals, for example, 290403353 + ... + 290403530.

It is an arithmetic number, because the mean of its divisors is an integer number (13068154890).

Almost surely, 2^51691812587 is an apocalyptic number.

51691812587 is a deficient number, since it is larger than the sum of its proper divisors (580806973).

51691812587 is an equidigital number, since it uses as much as digits as its factorization.

51691812587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 580806972.

The product of its digits is 1209600, while the sum is 53.

The spelling of 51691812587 in words is "fifty-one billion, six hundred ninety-one million, eight hundred twelve thousand, five hundred eighty-seven".