51890821 has 2 divisors, whose sum is σ = 51890822. Its totient is φ = 51890820.

The previous prime is 51890819. The next prime is 51890833. The reversal of 51890821 is 12809815.

51890821 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., 27772900 + 24117921 = 5270^2 + 4911^2 .

It is a cyclic number.

It is not a de Polignac number, because 51890821 - 2¹ = 51890819 is a prime.

Together with 51890819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51890801) 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, 25945410 + 25945411.

It is an arithmetic number, because the mean of its divisors is an integer number (25945411).

Almost surely, 2^51890821 is an apocalyptic number.

It is an amenable number.

51890821 is a deficient number, since it is larger than the sum of its proper divisors (1).

51890821 is an equidigital number, since it uses as much as digits as its factorization.

51890821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 51890821 is about 7203.5283715690. The cubic root of 51890821 is about 372.9897071098.

The spelling of 51890821 in words is "fifty-one million, eight hundred ninety thousand, eight hundred twenty-one".