51319781 has 2 divisors, whose sum is σ = 51319782. Its totient is φ = 51319780.

The previous prime is 51319771. The next prime is 51319783. The reversal of 51319781 is 18791315.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 25908100 + 25411681 = 5090^2 + 5041^2 .

It is a cyclic number.

It is not a de Polignac number, because 51319781 - 2¹⁸ = 51057637 is a prime.

It is a super-2 number, since 2×51319781² = 5267439843775922, which contains 22 as substring.

Together with 51319783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51319783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25659890 + 25659891.

It is an arithmetic number, because the mean of its divisors is an integer number (25659891).

Almost surely, 2^51319781 is an apocalyptic number.

It is an amenable number.

51319781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51319781 is an equidigital number, since it uses as much as digits as its factorization.

51319781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7560, while the sum is 35.

The square root of 51319781 is about 7163.7825902242. The cubic root of 51319781 is about 371.6164510393.

The spelling of 51319781 in words is "fifty-one million, three hundred nineteen thousand, seven hundred eighty-one".