221660009 has 4 divisors (see below), whose sum is σ = 223621716. Its totient is φ = 219698304.

The previous prime is 221660003. The next prime is 221660029. The reversal of 221660009 is 900066122.

221660009 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 6744409 + 214915600 = 2597^2 + 14660^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221660009 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221660009.

It is not an unprimeable number, because it can be changed into a prime (221660003) 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, 980684 + ... + 980909.

It is an arithmetic number, because the mean of its divisors is an integer number (55905429).

Almost surely, 2^221660009 is an apocalyptic number.

It is an amenable number.

221660009 is a deficient number, since it is larger than the sum of its proper divisors (1961707).

221660009 is a wasteful number, since it uses less digits than its factorization.

221660009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1961706.

The product of its (nonzero) digits is 1296, while the sum is 26.

The square root of 221660009 is about 14888.2507031552. The cubic root of 221660009 is about 605.1956282874.

The spelling of 221660009 in words is "two hundred twenty-one million, six hundred sixty thousand, nine".