221991236 has 24 divisors (see below), whose sum is σ = 412145496. Its totient is φ = 104261120.

The previous prime is 221991221. The next prime is 221991247. The reversal of 221991236 is 632199122.

It can be written as a sum of positive squares in 4 ways, for example, as 16240900 + 205750336 = 4030^2 + 14344^2 .

It is a junction number, because it is equal to n+sod(n) for n = 221991196 and 221991205.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 34946 + ... + 40806.

It is an arithmetic number, because the mean of its divisors is an integer number (17172729).

Almost surely, 2^221991236 is an apocalyptic number.

It is an amenable number.

221991236 is a deficient number, since it is larger than the sum of its proper divisors (190154260).

221991236 is a wasteful number, since it uses less digits than its factorization.

221991236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6439 (or 6437 counting only the distinct ones).

The product of its digits is 11664, while the sum is 35.

The square root of 221991236 is about 14899.3703222653. The cubic root of 221991236 is about 605.4969266110.

The spelling of 221991236 in words is "two hundred twenty-one million, nine hundred ninety-one thousand, two hundred thirty-six".