221617440 has 288 divisors, whose sum is σ = 874613376. Its totient is φ = 50503680.

The previous prime is 221617427. The next prime is 221617447. The reversal of 221617440 is 44716122.

221617440 is a `hidden beast` number, since 2 + 2 + 1 + 617 + 4 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×221617440² = 98228579424307200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221617447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 268869 + ... + 269691.

It is an arithmetic number, because the mean of its divisors is an integer number (3036852).

Almost surely, 2^221617440 is an apocalyptic number.

221617440 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 221617440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (437306688).

221617440 is an abundant number, since it is smaller than the sum of its proper divisors (652995936).

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

221617440 is a wasteful number, since it uses less digits than its factorization.

221617440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 872 (or 861 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 221617440 is about 14886.8210172622. The cubic root of 221617440 is about 605.1568839326.

The spelling of 221617440 in words is "two hundred twenty-one million, six hundred seventeen thousand, four hundred forty".