51451781 has 2 divisors, whose sum is σ = 51451782. Its totient is φ = 51451780.

The previous prime is 51451769. The next prime is 51451811. The reversal of 51451781 is 18715415.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38019556 + 13432225 = 6166^2 + 3665^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51451781 is a prime.

It is a super-2 number, since 2×51451781² = 5294571536143922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51451721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25725890 + 25725891.

It is an arithmetic number, because the mean of its divisors is an integer number (25725891).

Almost surely, 2^51451781 is an apocalyptic number.

It is an amenable number.

51451781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51451781 is an equidigital number, since it uses as much as digits as its factorization.

51451781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5600, while the sum is 32.

The square root of 51451781 is about 7172.9896835281. The cubic root of 51451781 is about 371.9347907628.

The spelling of 51451781 in words is "fifty-one million, four hundred fifty-one thousand, seven hundred eighty-one".