221809057 has 4 divisors (see below), whose sum is σ = 227219076. Its totient is φ = 216399040.

The previous prime is 221809001. The next prime is 221809067. The reversal of 221809057 is 750908122.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8532241 + 213276816 = 2921^2 + 14604^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221809057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221809067) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2704948 + ... + 2705029.

It is an arithmetic number, because the mean of its divisors is an integer number (56804769).

Almost surely, 2^221809057 is an apocalyptic number.

It is an amenable number.

221809057 is a deficient number, since it is larger than the sum of its proper divisors (5410019).

221809057 is an equidigital number, since it uses as much as digits as its factorization.

221809057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5410018.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 221809057 is about 14893.2554198201. The cubic root of 221809057 is about 605.3312458756.

The spelling of 221809057 in words is "two hundred twenty-one million, eight hundred nine thousand, fifty-seven".