90172321 has 4 divisors (see below), whose sum is σ = 90999700. Its totient is φ = 89344944.

The previous prime is 90172289. The next prime is 90172331. The reversal of 90172321 is 12327109.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 71639296 + 18533025 = 8464^2 + 4305^2 .

It is a cyclic number.

It is not a de Polignac number, because 90172321 - 2⁵ = 90172289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90172331) 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, 413526 + ... + 413743.

It is an arithmetic number, because the mean of its divisors is an integer number (22749925).

Almost surely, 2^90172321 is an apocalyptic number.

It is an amenable number.

90172321 is a deficient number, since it is larger than the sum of its proper divisors (827379).

90172321 is a wasteful number, since it uses less digits than its factorization.

90172321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 827378.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 90172321 is about 9495.9107514761. The cubic root of 90172321 is about 448.4263071769.

The spelling of 90172321 in words is "ninety million, one hundred seventy-two thousand, three hundred twenty-one".