221605899 has 4 divisors (see below), whose sum is σ = 295474536. Its totient is φ = 147737264.

The previous prime is 221605889. The next prime is 221605903. The reversal of 221605899 is 998506122.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 221605899 - 2¹³ = 221597707 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221605899.

It is not an unprimeable number, because it can be changed into a prime (221605889) 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 in 3 ways as a sum of consecutive naturals, for example, 36934314 + ... + 36934319.

It is an arithmetic number, because the mean of its divisors is an integer number (73868634).

Almost surely, 2^221605899 is an apocalyptic number.

221605899 is a deficient number, since it is larger than the sum of its proper divisors (73868637).

221605899 is an equidigital number, since it uses as much as digits as its factorization.

221605899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73868636.

The product of its (nonzero) digits is 77760, while the sum is 42.

The square root of 221605899 is about 14886.4333874841. The cubic root of 221605899 is about 605.1463789880.

The spelling of 221605899 in words is "two hundred twenty-one million, six hundred five thousand, eight hundred ninety-nine".