19723609 has 2 divisors, whose sum is σ = 19723610. Its totient is φ = 19723608.

The previous prime is 19723607. The next prime is 19723619. The reversal of 19723609 is 90632791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19360000 + 363609 = 4400^2 + 603^2 .

It is a cyclic number.

It is not a de Polignac number, because 19723609 - 2¹ = 19723607 is a prime.

Together with 19723607, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (19723603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9861804 + 9861805.

It is an arithmetic number, because the mean of its divisors is an integer number (9861805).

Almost surely, 2^19723609 is an apocalyptic number.

It is an amenable number.

19723609 is a deficient number, since it is larger than the sum of its proper divisors (1).

19723609 is an equidigital number, since it uses as much as digits as its factorization.

19723609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 19723609 is about 4441.1269966080. The cubic root of 19723609 is about 270.1855560332.

The spelling of 19723609 in words is "nineteen million, seven hundred twenty-three thousand, six hundred nine".