217923713329 has 21 divisors (see below), whose sum is σ = 254430967531. Its totient is φ = 186654508320.

The previous prime is 217923713291. The next prime is 217923713389. The reversal of 217923713329 is 923317329712.

It is a happy number.

The square root of 217923713329 is 466823.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 37026610929 + 180897102400 = 192423^2 + 425320^2 .

It is a de Polignac number, because none of the positive numbers 2^k-217923713329 is a prime.

It is a super-2 number, since 2×217923713329² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217923713389) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 160119609 + ... + 160120969.

Almost surely, 2^217923713329 is an apocalyptic number.

217923713329 is the 466823-rd square number.

217923713329 is the 233412-nd centered octagonal number.

It is an amenable number.

217923713329 is a deficient number, since it is larger than the sum of its proper divisors (36507254202).

217923713329 is an frugal number, since it uses more digits than its factorization.

217923713329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2764 (or 1368 counting only the distinct ones).

The product of its digits is 857304, while the sum is 49.

Multiplying 217923713329 by its sum of digits (49), we get a square (10678261953121 = 3267761²).

217923713329 divided by its sum of digits (49) gives a square (4447422721 = 66689²).

The spelling of 217923713329 in words is "two hundred seventeen billion, nine hundred twenty-three million, seven hundred thirteen thousand, three hundred twenty-nine".