221640635 has 8 divisors (see below), whose sum is σ = 268711296. Its totient is φ = 175484160.

The previous prime is 221640599. The next prime is 221640637. The reversal of 221640635 is 536046122.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 221640635 - 2⁸ = 221640379 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221640598 and 221640607.

It is not an unprimeable number, because it can be changed into a prime (221640637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 228011 + ... + 228980.

It is an arithmetic number, because the mean of its divisors is an integer number (33588912).

Almost surely, 2^221640635 is an apocalyptic number.

221640635 is a deficient number, since it is larger than the sum of its proper divisors (47070661).

221640635 is an equidigital number, since it uses as much as digits as its factorization.

221640635 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 457093.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 221640635 is about 14887.6000416454. The cubic root of 221640635 is about 605.1779955748.

Adding to 221640635 its reverse (536046122), we get a palindrome (757686757).

The spelling of 221640635 in words is "two hundred twenty-one million, six hundred forty thousand, six hundred thirty-five".