19740209 has 2 divisors, whose sum is σ = 19740210. Its totient is φ = 19740208.

The previous prime is 19740199. The next prime is 19740239. The reversal of 19740209 is 90204791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18879025 + 861184 = 4345^2 + 928^2 .

It is an emirp because it is prime and its reverse (90204791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19740209 - 2¹² = 19736113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19740239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9870104 + 9870105.

It is an arithmetic number, because the mean of its divisors is an integer number (9870105).

Almost surely, 2^19740209 is an apocalyptic number.

It is an amenable number.

19740209 is a deficient number, since it is larger than the sum of its proper divisors (1).

19740209 is an equidigital number, since it uses as much as digits as its factorization.

19740209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 32.

The square root of 19740209 is about 4442.9954985347. The cubic root of 19740209 is about 270.2613336214.

The spelling of 19740209 in words is "nineteen million, seven hundred forty thousand, two hundred nine".