72156209 has 2 divisors, whose sum is σ = 72156210. Its totient is φ = 72156208.

The previous prime is 72156173. The next prime is 72156239. The reversal of 72156209 is 90265127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66994225 + 5161984 = 8185^2 + 2272^2 .

It is a cyclic number.

It is not a de Polignac number, because 72156209 - 2⁸ = 72155953 is a prime.

It is not a weakly prime, because it can be changed into another prime (72156239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36078104 + 36078105.

It is an arithmetic number, because the mean of its divisors is an integer number (36078105).

Almost surely, 2^72156209 is an apocalyptic number.

It is an amenable number.

72156209 is a deficient number, since it is larger than the sum of its proper divisors (1).

72156209 is an equidigital number, since it uses as much as digits as its factorization.

72156209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 32.

The square root of 72156209 is about 8494.4810906847. The cubic root of 72156209 is about 416.3174063810.

The spelling of 72156209 in words is "seventy-two million, one hundred fifty-six thousand, two hundred nine".