217972799 has 4 divisors (see below), whose sum is σ = 237788520. Its totient is φ = 198157080.

The previous prime is 217972789. The next prime is 217972801. The reversal of 217972799 is 997279712.

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

It is a de Polignac number, because none of the positive numbers 2^k-217972799 is a prime.

It is a super-2 number, since 2×217972799² = 95024282207788802, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a self number, because there is not a number n which added to its sum of digits gives 217972799.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217972709) 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, 9907844 + ... + 9907865.

It is an arithmetic number, because the mean of its divisors is an integer number (59447130).

Almost surely, 2^217972799 is an apocalyptic number.

217972799 is a deficient number, since it is larger than the sum of its proper divisors (19815721).

217972799 is a wasteful number, since it uses less digits than its factorization.

217972799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19815720.

The product of its digits is 1000188, while the sum is 53.

The square root of 217972799 is about 14763.9018894058. The cubic root of 217972799 is about 601.8211326083.

The spelling of 217972799 in words is "two hundred seventeen million, nine hundred seventy-two thousand, seven hundred ninety-nine".