217320445 has 8 divisors (see below), whose sum is σ = 272123136. Its totient is φ = 166297296.

The previous prime is 217320437. The next prime is 217320457. The reversal of 217320445 is 544023712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 217320445 - 2³ = 217320437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 944757 + ... + 944986.

It is an arithmetic number, because the mean of its divisors is an integer number (34015392).

Almost surely, 2^217320445 is an apocalyptic number.

It is an amenable number.

217320445 is a deficient number, since it is larger than the sum of its proper divisors (54802691).

217320445 is a wasteful number, since it uses less digits than its factorization.

217320445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1889771.

The product of its (nonzero) digits is 6720, while the sum is 28.

The square root of 217320445 is about 14741.7924622483. The cubic root of 217320445 is about 601.2201512953.

It can be divided in two parts, 21 and 7320445, that multiplied together give a triangular number (153729345 = T₁₇₅₃₄).

The spelling of 217320445 in words is "two hundred seventeen million, three hundred twenty thousand, four hundred forty-five".