170551921 has 2 divisors, whose sum is σ = 170551922. Its totient is φ = 170551920.

The previous prime is 170551919. The next prime is 170551937. The reversal of 170551921 is 129155071.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 164480625 + 6071296 = 12825^2 + 2464^2 .

It is a cyclic number.

It is not a de Polignac number, because 170551921 - 2¹ = 170551919 is a prime.

Together with 170551919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (170551421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85275960 + 85275961.

It is an arithmetic number, because the mean of its divisors is an integer number (85275961).

Almost surely, 2^170551921 is an apocalyptic number.

It is an amenable number.

170551921 is a deficient number, since it is larger than the sum of its proper divisors (1).

170551921 is an equidigital number, since it uses as much as digits as its factorization.

170551921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3150, while the sum is 31.

The square root of 170551921 is about 13059.5528637086. The cubic root of 170551921 is about 554.5646787949.

Adding to 170551921 its product of nonzero digits (3150), we get a palindrome (170555071).

The spelling of 170551921 in words is "one hundred seventy million, five hundred fifty-one thousand, nine hundred twenty-one".