57156821 has 2 divisors, whose sum is σ = 57156822. Its totient is φ = 57156820.

The previous prime is 57156763. The next prime is 57156859. The reversal of 57156821 is 12865175.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41860900 + 15295921 = 6470^2 + 3911^2 .

It is a cyclic number.

It is not a de Polignac number, because 57156821 - 2²² = 52962517 is a prime.

It is a Sophie Germain 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 (57156521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28578410 + 28578411.

It is an arithmetic number, because the mean of its divisors is an integer number (28578411).

Almost surely, 2^57156821 is an apocalyptic number.

It is an amenable number.

57156821 is a deficient number, since it is larger than the sum of its proper divisors (1).

57156821 is an equidigital number, since it uses as much as digits as its factorization.

57156821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16800, while the sum is 35.

The square root of 57156821 is about 7560.2130260992. The cubic root of 57156821 is about 385.2027290094.

The spelling of 57156821 in words is "fifty-seven million, one hundred fifty-six thousand, eight hundred twenty-one".