221405644 has 6 divisors (see below), whose sum is σ = 387459884. Its totient is φ = 110702820.

The previous prime is 221405623. The next prime is 221405647. The reversal of 221405644 is 446504122.

It is not an unprimeable number, because it can be changed into a prime (221405647) 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 as a sum of consecutive naturals, namely, 27675702 + ... + 27675709.

Almost surely, 2^221405644 is an apocalyptic number.

It is an amenable number.

221405644 is a deficient number, since it is larger than the sum of its proper divisors (166054240).

221405644 is a wasteful number, since it uses less digits than its factorization.

221405644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55351415 (or 55351413 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 28.

The square root of 221405644 is about 14879.7057766610. The cubic root of 221405644 is about 604.9640431240.

Adding to 221405644 its reverse (446504122), we get a palindrome (667909766).

The spelling of 221405644 in words is "two hundred twenty-one million, four hundred five thousand, six hundred forty-four".