171280721 has 2 divisors, whose sum is σ = 171280722. Its totient is φ = 171280720.

The previous prime is 171280667. The next prime is 171280723. The reversal of 171280721 is 127082171.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166281025 + 4999696 = 12895^2 + 2236^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-171280721 is a prime.

Together with 171280723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (171280723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85640360 + 85640361.

It is an arithmetic number, because the mean of its divisors is an integer number (85640361).

Almost surely, 2^171280721 is an apocalyptic number.

It is an amenable number.

171280721 is a deficient number, since it is larger than the sum of its proper divisors (1).

171280721 is an equidigital number, since it uses as much as digits as its factorization.

171280721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 29.

The square root of 171280721 is about 13087.4260647386. The cubic root of 171280721 is about 555.3534755539.

The spelling of 171280721 in words is "one hundred seventy-one million, two hundred eighty thousand, seven hundred twenty-one".