217121280 has 160 divisors (see below), whose sum is σ = 735381504. Its totient is φ = 54460416.

The previous prime is 217121273. The next prime is 217121287. The reversal of 217121280 is 82121712.

217121280 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (217121273) and next prime (217121287).

It is a tau number, because it is divible by the number of its divisors (160).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 217121280.

It is not an unprimeable number, because it can be changed into a prime (217121287) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 129729 + ... + 131391.

Almost surely, 2^217121280 is an apocalyptic number.

217121280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 217121280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (367690752).

217121280 is an abundant number, since it is smaller than the sum of its proper divisors (518260224).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

217121280 is a wasteful number, since it uses less digits than its factorization.

217121280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1706 (or 1690 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 24.

The square root of 217121280 is about 14735.0357990743. The cubic root of 217121280 is about 601.0364308764.

Adding to 217121280 its reverse (82121712), we get a palindrome (299242992).

The spelling of 217121280 in words is "two hundred seventeen million, one hundred twenty-one thousand, two hundred eighty".