217665140 has 192 divisors, whose sum is σ = 617379840. Its totient is φ = 62415360.

The previous prime is 217665139. The next prime is 217665163. The reversal of 217665140 is 41566712.

It is a super-2 number, since 2×217665140² = 94756226342439200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 217665097 and 217665106.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1258094 + ... + 1258266.

It is an arithmetic number, because the mean of its divisors is an integer number (3215520).

Almost surely, 2^217665140 is an apocalyptic number.

217665140 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 217665140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (308689920).

217665140 is an abundant number, since it is smaller than the sum of its proper divisors (399714700).

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

217665140 is a wasteful number, since it uses less digits than its factorization.

217665140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262 (or 260 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 217665140 is about 14753.4789117686. The cubic root of 217665140 is about 601.5378512844.

The spelling of 217665140 in words is "two hundred seventeen million, six hundred sixty-five thousand, one hundred forty".