72218609 has 4 divisors (see below), whose sum is σ = 72479604. Its totient is φ = 71957616.

The previous prime is 72218599. The next prime is 72218647. The reversal of 72218609 is 90681227.

It is a happy number.

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 13359025 + 58859584 = 3655^2 + 7672^2 .

It is a cyclic number.

It is not a de Polignac number, because 72218609 - 2⁸ = 72218353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72218659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 130082 + ... + 130635.

It is an arithmetic number, because the mean of its divisors is an integer number (18119901).

Almost surely, 2^72218609 is an apocalyptic number.

It is an amenable number.

72218609 is a deficient number, since it is larger than the sum of its proper divisors (260995).

72218609 is a wasteful number, since it uses less digits than its factorization.

72218609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260994.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 72218609 is about 8498.1532699758. The cubic root of 72218609 is about 416.4373809082.

It can be divided in two parts, 72218 and 609, that added together give a palindrome (72827).

The spelling of 72218609 in words is "seventy-two million, two hundred eighteen thousand, six hundred nine".