171981913 has 2 divisors, whose sum is σ = 171981914. Its totient is φ = 171981912.

The previous prime is 171981907. The next prime is 171981923. The reversal of 171981913 is 319189171.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156950784 + 15031129 = 12528^2 + 3877^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-171981913 is a prime.

It is equal to p_9607729 and since 171981913 and 9607729 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (171981923) 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, 85990956 + 85990957.

It is an arithmetic number, because the mean of its divisors is an integer number (85990957).

Almost surely, 2^171981913 is an apocalyptic number.

It is an amenable number.

171981913 is a deficient number, since it is larger than the sum of its proper divisors (1).

171981913 is an equidigital number, since it uses as much as digits as its factorization.

171981913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13608, while the sum is 40.

The square root of 171981913 is about 13114.1874700646. The cubic root of 171981913 is about 556.1102823268.

The spelling of 171981913 in words is "one hundred seventy-one million, nine hundred eighty-one thousand, nine hundred thirteen".