217021240 has 32 divisors (see below), whose sum is σ = 489196080. Its totient is φ = 86648832.

The previous prime is 217021237. The next prime is 217021253. The reversal of 217021240 is 42120712.

It is a happy number.

It is a super-2 number, since 2×217021240² = 94196437222275200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18379 + ... + 27781.

Almost surely, 2^217021240 is an apocalyptic number.

217021240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

217021240 is an abundant number, since it is smaller than the sum of its proper divisors (272174840).

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

217021240 is a wasteful number, since it uses less digits than its factorization.

217021240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9991 (or 9987 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 217021240 is about 14731.6407775916. The cubic root of 217021240 is about 600.9441062524.

Adding to 217021240 its reverse (42120712), we get a palindrome (259141952).

The spelling of 217021240 in words is "two hundred seventeen million, twenty-one thousand, two hundred forty".