72189209 has 2 divisors, whose sum is σ = 72189210. Its totient is φ = 72189208.

The previous prime is 72189197. The next prime is 72189263. The reversal of 72189209 is 90298127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45697600 + 26491609 = 6760^2 + 5147^2 .

It is a cyclic number.

It is not a de Polignac number, because 72189209 - 2⁴ = 72189193 is a prime.

It is a super-2 number, since 2×72189209² = 10422563792091362, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (72189409) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36094604 + 36094605.

It is an arithmetic number, because the mean of its divisors is an integer number (36094605).

Almost surely, 2^72189209 is an apocalyptic number.

It is an amenable number.

72189209 is a deficient number, since it is larger than the sum of its proper divisors (1).

72189209 is an equidigital number, since it uses as much as digits as its factorization.

72189209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 72189209 is about 8496.4233063095. The cubic root of 72189209 is about 416.3808630617.

The spelling of 72189209 in words is "seventy-two million, one hundred eighty-nine thousand, two hundred nine".