172016321 has 4 divisors (see below), whose sum is σ = 172042692. Its totient is φ = 171989952.

The previous prime is 172016309. The next prime is 172016363. The reversal of 172016321 is 123610271.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 108972721 + 63043600 = 10439^2 + 7940^2 .

It is a cyclic number.

It is not a de Polignac number, because 172016321 - 2¹⁰ = 172015297 is a prime.

It is a super-2 number, since 2×172016321² = 59179229380750082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (172016021) 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, 4565 + ... + 19101.

It is an arithmetic number, because the mean of its divisors is an integer number (43010673).

Almost surely, 2^172016321 is an apocalyptic number.

It is an amenable number.

172016321 is a deficient number, since it is larger than the sum of its proper divisors (26371).

172016321 is a wasteful number, since it uses less digits than its factorization.

172016321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26370.

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 172016321 is about 13115.4992661355. The cubic root of 172016321 is about 556.1473663944.

Adding to 172016321 its reverse (123610271), we get a palindrome (295626592).

The spelling of 172016321 in words is "one hundred seventy-two million, sixteen thousand, three hundred twenty-one".