172216309 has 4 divisors (see below), whose sum is σ = 173888416. Its totient is φ = 170544204.

The previous prime is 172216259. The next prime is 172216313. The reversal of 172216309 is 903612271.

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 not a de Polignac number, because 172216309 - 2²³ = 163827701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172216379) 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 in 3 ways as a sum of consecutive naturals, for example, 835899 + ... + 836104.

It is an arithmetic number, because the mean of its divisors is an integer number (43472104).

Almost surely, 2^172216309 is an apocalyptic number.

It is an amenable number.

172216309 is a deficient number, since it is larger than the sum of its proper divisors (1672107).

172216309 is a wasteful number, since it uses less digits than its factorization.

172216309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1672106.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 172216309 is about 13123.1211607605. The cubic root of 172216309 is about 556.3628105332.

The spelling of 172216309 in words is "one hundred seventy-two million, two hundred sixteen thousand, three hundred nine".