51519781 has 2 divisors, whose sum is σ = 51519782. Its totient is φ = 51519780.

The previous prime is 51519779. The next prime is 51519817. The reversal of 51519781 is 18791515.

Together with next prime (51519817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34222500 + 17297281 = 5850^2 + 4159^2 .

It is a cyclic number.

It is not a de Polignac number, because 51519781 - 2¹ = 51519779 is a prime.

It is a super-2 number, since 2×51519781² = 5308575668575922, which contains 22 as substring.

Together with 51519779, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 51519781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51519761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25759890 + 25759891.

It is an arithmetic number, because the mean of its divisors is an integer number (25759891).

Almost surely, 2^51519781 is an apocalyptic number.

It is an amenable number.

51519781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51519781 is an equidigital number, since it uses as much as digits as its factorization.

51519781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12600, while the sum is 37.

The square root of 51519781 is about 7177.7281224633. The cubic root of 51519781 is about 372.0985715006.

The spelling of 51519781 in words is "fifty-one million, five hundred nineteen thousand, seven hundred eighty-one".