51855821 has 2 divisors, whose sum is σ = 51855822. Its totient is φ = 51855820.

The previous prime is 51855809. The next prime is 51855841. The reversal of 51855821 is 12855815.

51855821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37332100 + 14523721 = 6110^2 + 3811^2 .

It is a cyclic number.

It is not a de Polignac number, because 51855821 - 2²² = 47661517 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51855841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25927910 + 25927911.

It is an arithmetic number, because the mean of its divisors is an integer number (25927911).

Almost surely, 2^51855821 is an apocalyptic number.

It is an amenable number.

51855821 is a deficient number, since it is larger than the sum of its proper divisors (1).

51855821 is an equidigital number, since it uses as much as digits as its factorization.

51855821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16000, while the sum is 35.

The square root of 51855821 is about 7201.0985967420. The cubic root of 51855821 is about 372.9058285890.

The spelling of 51855821 in words is "fifty-one million, eight hundred fifty-five thousand, eight hundred twenty-one".