221601656 has 8 divisors (see below), whose sum is σ = 415503120. Its totient is φ = 110800824.

The previous prime is 221601649. The next prime is 221601689. The reversal of 221601656 is 656106122.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13850096 + ... + 13850111.

It is an arithmetic number, because the mean of its divisors is an integer number (51937890).

Almost surely, 2^221601656 is an apocalyptic number.

It is an amenable number.

221601656 is a deficient number, since it is larger than the sum of its proper divisors (193901464).

221601656 is a wasteful number, since it uses less digits than its factorization.

221601656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27700213 (or 27700209 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 221601656 is about 14886.2908744925. The cubic root of 221601656 is about 605.1425167976.

Adding to 221601656 its reverse (656106122), we get a palindrome (877707778).

The spelling of 221601656 in words is "two hundred twenty-one million, six hundred one thousand, six hundred fifty-six".