51991758349 has 4 divisors (see below), whose sum is σ = 51992216064. Its totient is φ = 51991300636.

The previous prime is 51991758311. The next prime is 51991758421. The reversal of 51991758349 is 94385719915.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 51991758349 - 2⁹ = 51991757837 is a prime.

It is a super-2 number, since 2×51991758349² (a number of 22 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 (51991758649) 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, 85044 + ... + 333490.

It is an arithmetic number, because the mean of its divisors is an integer number (12998054016).

Almost surely, 2^51991758349 is an apocalyptic number.

It is an amenable number.

51991758349 is a deficient number, since it is larger than the sum of its proper divisors (457715).

51991758349 is a wasteful number, since it uses less digits than its factorization.

51991758349 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457714.

The product of its digits is 12247200, while the sum is 61.

It can be divided in two parts, 5199175 and 8349, that added together give a square (5207524 = 2282²).

The spelling of 51991758349 in words is "fifty-one billion, nine hundred ninety-one million, seven hundred fifty-eight thousand, three hundred forty-nine".