16171021 has 2 divisors, whose sum is σ = 16171022. Its totient is φ = 16171020.

The previous prime is 16171019. The next prime is 16171027. The reversal of 16171021 is 12017161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11655396 + 4515625 = 3414^2 + 2125^2 .

It is a cyclic number.

It is not a de Polignac number, because 16171021 - 2¹ = 16171019 is a prime.

Together with 16171019, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 16171021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16171027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8085510 + 8085511.

It is an arithmetic number, because the mean of its divisors is an integer number (8085511).

Almost surely, 2^16171021 is an apocalyptic number.

It is an amenable number.

16171021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16171021 is an equidigital number, since it uses as much as digits as its factorization.

16171021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 84, while the sum is 19.

The square root of 16171021 is about 4021.3208029204. The cubic root of 16171021 is about 252.8788340116.

Adding to 16171021 its reverse (12017161), we get a palindrome (28188182).

The spelling of 16171021 in words is "sixteen million, one hundred seventy-one thousand, twenty-one".