57212821 has 2 divisors, whose sum is σ = 57212822. Its totient is φ = 57212820.

The previous prime is 57212797. The next prime is 57212839. The reversal of 57212821 is 12821275.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57168721 + 44100 = 7561^2 + 210^2 .

It is a cyclic number.

It is not a de Polignac number, because 57212821 - 2⁵ = 57212789 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 57212821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (57212851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28606410 + 28606411.

It is an arithmetic number, because the mean of its divisors is an integer number (28606411).

Almost surely, 2^57212821 is an apocalyptic number.

It is an amenable number.

57212821 is a deficient number, since it is larger than the sum of its proper divisors (1).

57212821 is an equidigital number, since it uses as much as digits as its factorization.

57212821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2240, while the sum is 28.

The square root of 57212821 is about 7563.9157187266. The cubic root of 57212821 is about 385.3284900960.

It can be divided in two parts, 57 and 212821, that added together give a triangular number (212878 = T₆₅₂).

The spelling of 57212821 in words is "fifty-seven million, two hundred twelve thousand, eight hundred twenty-one".