16857121 has 2 divisors, whose sum is σ = 16857122. Its totient is φ = 16857120.

The previous prime is 16857119. The next prime is 16857157. The reversal of 16857121 is 12175861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10923025 + 5934096 = 3305^2 + 2436^2 .

It is a cyclic number.

It is not a de Polignac number, because 16857121 - 2¹ = 16857119 is a prime.

Together with 16857119, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (16857821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8428560 + 8428561.

It is an arithmetic number, because the mean of its divisors is an integer number (8428561).

Almost surely, 2^16857121 is an apocalyptic number.

It is an amenable number.

16857121 is a deficient number, since it is larger than the sum of its proper divisors (1).

16857121 is an equidigital number, since it uses as much as digits as its factorization.

16857121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 31.

The square root of 16857121 is about 4105.7424419951. The cubic root of 16857121 is about 256.4057743318.

The spelling of 16857121 in words is "sixteen million, eight hundred fifty-seven thousand, one hundred twenty-one".