19908689 has 2 divisors, whose sum is σ = 19908690. Its totient is φ = 19908688.

The previous prime is 19908673. The next prime is 19908697. The reversal of 19908689 is 98680991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15840400 + 4068289 = 3980^2 + 2017^2 .

It is an emirp because it is prime and its reverse (98680991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19908689 - 2⁴ = 19908673 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19908289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9954344 + 9954345.

It is an arithmetic number, because the mean of its divisors is an integer number (9954345).

Almost surely, 2^19908689 is an apocalyptic number.

It is an amenable number.

19908689 is a deficient number, since it is larger than the sum of its proper divisors (1).

19908689 is an equidigital number, since it uses as much as digits as its factorization.

19908689 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 279936, while the sum is 50.

The square root of 19908689 is about 4461.9153958810. The cubic root of 19908689 is about 271.0280377485.

The spelling of 19908689 in words is "nineteen million, nine hundred eight thousand, six hundred eighty-nine".