221716656 has 160 divisors (see below), whose sum is σ = 733524480. Its totient is φ = 62809344.

The previous prime is 221716637. The next prime is 221716679. The reversal of 221716656 is 656617122.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 221716656.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 474535 + ... + 475001.

It is an arithmetic number, because the mean of its divisors is an integer number (4584528).

Almost surely, 2^221716656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 221716656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (366762240).

221716656 is an abundant number, since it is smaller than the sum of its proper divisors (511807824).

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

221716656 is a wasteful number, since it uses less digits than its factorization.

221716656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648 (or 636 counting only the distinct ones).

The product of its digits is 30240, while the sum is 36.

The square root of 221716656 is about 14890.1529877970. The cubic root of 221716656 is about 605.2471781015.

The spelling of 221716656 in words is "two hundred twenty-one million, seven hundred sixteen thousand, six hundred fifty-six".