51331697749 has 4 divisors (see below), whose sum is σ = 51338505100. Its totient is φ = 51324890400.

The previous prime is 51331697743. The next prime is 51331697803. The reversal of 51331697749 is 94779613315.

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 44804188900 + 6527508849 = 211670^2 + 80793^2 .

It is a cyclic number.

It is not a de Polignac number, because 51331697749 - 2¹⁵ = 51331664981 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51331697749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51331697743) 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, 3392352 + ... + 3407449.

It is an arithmetic number, because the mean of its divisors is an integer number (12834626275).

Almost surely, 2^51331697749 is an apocalyptic number.

It is an amenable number.

51331697749 is a deficient number, since it is larger than the sum of its proper divisors (6807351).

51331697749 is an equidigital number, since it uses as much as digits as its factorization.

51331697749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6807350.

The product of its digits is 4286520, while the sum is 55.

It can be divided in two parts, 513316 and 97749, that added together give a triangular number (611065 = T₁₁₀₅).

The spelling of 51331697749 in words is "fifty-one billion, three hundred thirty-one million, six hundred ninety-seven thousand, seven hundred forty-nine".