221020636 has 6 divisors (see below), whose sum is σ = 386786120. Its totient is φ = 110510316.

The previous prime is 221020561. The next prime is 221020637. The reversal of 221020636 is 636020122.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221020637) 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, 27627576 + ... + 27627583.

Almost surely, 2^221020636 is an apocalyptic number.

It is an amenable number.

221020636 is a deficient number, since it is larger than the sum of its proper divisors (165765484).

221020636 is a wasteful number, since it uses less digits than its factorization.

221020636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55255163 (or 55255161 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 221020636 is about 14866.7627949060. The cubic root of 221020636 is about 604.6131771290.

Adding to 221020636 its reverse (636020122), we get a palindrome (857040758).

The spelling of 221020636 in words is "two hundred twenty-one million, twenty thousand, six hundred thirty-six".