170921 has 2 divisors, whose sum is σ = 170922. Its totient is φ = 170920.

The previous prime is 170899. The next prime is 170927. The reversal of 170921 is 129071.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 151321 + 19600 = 389^2 + 140^2 .

It is a cyclic number.

It is not a de Polignac number, because 170921 - 2⁶ = 170857 is a prime.

It is a Chen prime.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 170893 and 170902.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 170921.

It is not a weakly prime, because it can be changed into another prime (170927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85460 + 85461.

It is an arithmetic number, because the mean of its divisors is an integer number (85461).

2¹⁷⁰⁹²¹ is an apocalyptic number.

It is an amenable number.

170921 is a deficient number, since it is larger than the sum of its proper divisors (1).

170921 is an equidigital number, since it uses as much as digits as its factorization.

170921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 126, while the sum is 20.

The square root of 170921 is about 413.4259304882. The cubic root of 170921 is about 55.4964421603.

Adding to 170921 its reverse (129071), we get a palindrome (299992).

The spelling of 170921 in words is "one hundred seventy thousand, nine hundred twenty-one".