2171857 has 2 divisors, whose sum is σ = 2171858. Its totient is φ = 2171856.

The previous prime is 2171843. The next prime is 2171881. The reversal of 2171857 is 7581712.

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., 2143296 + 28561 = 1464^2 + 169^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2171857 is a prime.

It is not a weakly prime, because it can be changed into another prime (2171837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1085928 + 1085929.

It is an arithmetic number, because the mean of its divisors is an integer number (1085929).

2^2171857 is an apocalyptic number.

It is an amenable number.

2171857 is a deficient number, since it is larger than the sum of its proper divisors (1).

2171857 is an equidigital number, since it uses as much as digits as its factorization.

2171857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3920, while the sum is 31.

The square root of 2171857 is about 1473.7221583460. The cubic root of 2171857 is about 129.5021789211.

The spelling of 2171857 in words is "two million, one hundred seventy-one thousand, eight hundred fifty-seven".