221642636 has 6 divisors (see below), whose sum is σ = 387874620. Its totient is φ = 110821316.

The previous prime is 221642627. The next prime is 221642669. The reversal of 221642636 is 636246122.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27705326 + ... + 27705333.

It is an arithmetic number, because the mean of its divisors is an integer number (64645770).

Almost surely, 2^221642636 is an apocalyptic number.

It is an amenable number.

221642636 is a deficient number, since it is larger than the sum of its proper divisors (166231984).

221642636 is a wasteful number, since it uses less digits than its factorization.

221642636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55410663 (or 55410661 counting only the distinct ones).

The product of its digits is 20736, while the sum is 32.

The square root of 221642636 is about 14887.6672450723. The cubic root of 221642636 is about 605.1798167774.

Adding to 221642636 its reverse (636246122), we get a palindrome (857888758).

The spelling of 221642636 in words is "two hundred twenty-one million, six hundred forty-two thousand, six hundred thirty-six".