7940209 has 2 divisors, whose sum is σ = 7940210. Its totient is φ = 7940208.

The previous prime is 7940197. The next prime is 7940239. The reversal of 7940209 is 9020497.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4223025 + 3717184 = 2055^2 + 1928^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7940209 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7940239) 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, 3970104 + 3970105.

It is an arithmetic number, because the mean of its divisors is an integer number (3970105).

Almost surely, 2^7940209 is an apocalyptic number.

It is an amenable number.

7940209 is a deficient number, since it is larger than the sum of its proper divisors (1).

7940209 is an equidigital number, since it uses as much as digits as its factorization.

7940209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 7940209 is about 2817.8376461393. The cubic root of 7940209 is about 199.5004951799.

The spelling of 7940209 in words is "seven million, nine hundred forty thousand, two hundred nine".