19764989 has 2 divisors, whose sum is σ = 19764990. Its totient is φ = 19764988.

The previous prime is 19764973. The next prime is 19765013. The reversal of 19764989 is 98946791.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18852964 + 912025 = 4342^2 + 955^2 .

It is an emirp because it is prime and its reverse (98946791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19764989 - 2⁴ = 19764973 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 19764989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19764929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9882494 + 9882495.

It is an arithmetic number, because the mean of its divisors is an integer number (9882495).

Almost surely, 2^19764989 is an apocalyptic number.

It is an amenable number.

19764989 is a deficient number, since it is larger than the sum of its proper divisors (1).

19764989 is an equidigital number, since it uses as much as digits as its factorization.

19764989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 979776, while the sum is 53.

The square root of 19764989 is about 4445.7832830672. The cubic root of 19764989 is about 270.3743732132.

The spelling of 19764989 in words is "nineteen million, seven hundred sixty-four thousand, nine hundred eighty-nine".