217661245 has 16 divisors (see below), whose sum is σ = 275307840. Its totient is φ = 164744064.

The previous prime is 217661239. The next prime is 217661263. The reversal of 217661245 is 542166712.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217661245 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 217661245.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 123289 + ... + 125041.

It is an arithmetic number, because the mean of its divisors is an integer number (17206740).

Almost surely, 2^217661245 is an apocalyptic number.

It is an amenable number.

217661245 is a deficient number, since it is larger than the sum of its proper divisors (57646595).

217661245 is a wasteful number, since it uses less digits than its factorization.

217661245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3084.

The product of its digits is 20160, while the sum is 34.

The square root of 217661245 is about 14753.3469084137. The cubic root of 217661245 is about 601.5342631981.

The spelling of 217661245 in words is "two hundred seventeen million, six hundred sixty-one thousand, two hundred forty-five".