82171909 has 4 divisors (see below), whose sum is σ = 83162016. Its totient is φ = 81181804.

The previous prime is 82171891. The next prime is 82171937. The reversal of 82171909 is 90917128.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-82171909 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (82171009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 494929 + ... + 495094.

It is an arithmetic number, because the mean of its divisors is an integer number (20790504).

Almost surely, 2^82171909 is an apocalyptic number.

It is an amenable number.

82171909 is a deficient number, since it is larger than the sum of its proper divisors (990107).

82171909 is an equidigital number, since it uses as much as digits as its factorization.

82171909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990106.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 82171909 is about 9064.8722550293. The cubic root of 82171909 is about 434.7515364465.

It can be divided in two parts, 82 and 171909, that added together give a triangular number (171991 = T₅₈₆).

The spelling of 82171909 in words is "eighty-two million, one hundred seventy-one thousand, nine hundred nine".