221115664 has 80 divisors (see below), whose sum is σ = 539715456. Its totient is φ = 85248000.

The previous prime is 221115659. The next prime is 221115677. The reversal of 221115664 is 466511122.

221115664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 123544 + ... + 125320.

Almost surely, 2^221115664 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 221115664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (269857728).

221115664 is an abundant number, since it is smaller than the sum of its proper divisors (318599792).

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

221115664 is a wasteful number, since it uses less digits than its factorization.

221115664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1904 (or 1898 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 221115664 is about 14869.9584397536. The cubic root of 221115664 is about 604.6998160204.

Adding to 221115664 its reverse (466511122), we get a palindrome (687626786).

The spelling of 221115664 in words is "two hundred twenty-one million, one hundred fifteen thousand, six hundred sixty-four".