51381988685 has 8 divisors (see below), whose sum is σ = 61734606840. Its totient is φ = 41054777344.

The previous prime is 51381988673. The next prime is 51381988687. The reversal of 51381988685 is 58688918315.

It can be written as a sum of positive squares in 4 ways, for example, as 24350354116 + 27031634569 = 156046^2 + 164413^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 51381988685 - 2⁶ = 51381988621 is a prime.

It is a super-2 number, since 2×51381988685² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51381988687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6347252 + ... + 6355341.

It is an arithmetic number, because the mean of its divisors is an integer number (7716825855).

Almost surely, 2^51381988685 is an apocalyptic number.

It is an amenable number.

51381988685 is a deficient number, since it is larger than the sum of its proper divisors (10352618155).

51381988685 is a wasteful number, since it uses less digits than its factorization.

51381988685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12703407.

The product of its digits is 16588800, while the sum is 62.

The spelling of 51381988685 in words is "fifty-one billion, three hundred eighty-one million, nine hundred eighty-eight thousand, six hundred eighty-five".