171916621 has 2 divisors, whose sum is σ = 171916622. Its totient is φ = 171916620.

The previous prime is 171916603. The next prime is 171916637. The reversal of 171916621 is 126619171.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 171872100 + 44521 = 13110^2 + 211^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-171916621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (171917621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85958310 + 85958311.

It is an arithmetic number, because the mean of its divisors is an integer number (85958311).

Almost surely, 2^171916621 is an apocalyptic number.

It is an amenable number.

171916621 is a deficient number, since it is larger than the sum of its proper divisors (1).

171916621 is an equidigital number, since it uses as much as digits as its factorization.

171916621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4536, while the sum is 34.

The square root of 171916621 is about 13111.6978686972. The cubic root of 171916621 is about 556.0398986688.

The spelling of 171916621 in words is "one hundred seventy-one million, nine hundred sixteen thousand, six hundred twenty-one".