51802781 has 2 divisors, whose sum is σ = 51802782. Its totient is φ = 51802780.

The previous prime is 51802769. The next prime is 51802801. The reversal of 51802781 is 18720815.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49477156 + 2325625 = 7034^2 + 1525^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51802781 is a prime.

It is a super-2 number, since 2×51802781² = 5367056238667922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51802181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25901390 + 25901391.

It is an arithmetic number, because the mean of its divisors is an integer number (25901391).

Almost surely, 2^51802781 is an apocalyptic number.

It is an amenable number.

51802781 is a deficient number, since it is larger than the sum of its proper divisors (1).

51802781 is an equidigital number, since it uses as much as digits as its factorization.

51802781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 51802781 is about 7197.4148831369. The cubic root of 51802781 is about 372.7786447156.

The spelling of 51802781 in words is "fifty-one million, eight hundred two thousand, seven hundred eighty-one".