39728209 has 2 divisors, whose sum is σ = 39728210. Its totient is φ = 39728208.

The previous prime is 39728197. The next prime is 39728237. The reversal of 39728209 is 90282793.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39727809 + 400 = 6303^2 + 20^2 .

It is an emirp because it is prime and its reverse (90282793) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 39728209 - 2¹³ = 39720017 is a prime.

It is not a weakly prime, because it can be changed into another prime (39728309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19864104 + 19864105.

It is an arithmetic number, because the mean of its divisors is an integer number (19864105).

Almost surely, 2^39728209 is an apocalyptic number.

It is an amenable number.

39728209 is a deficient number, since it is larger than the sum of its proper divisors (1).

39728209 is an equidigital number, since it uses as much as digits as its factorization.

39728209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 39728209 is about 6303.0317308419. The cubic root of 39728209 is about 341.2188348323.

The spelling of 39728209 in words is "thirty-nine million, seven hundred twenty-eight thousand, two hundred nine".