19647989 has 2 divisors, whose sum is σ = 19647990. Its totient is φ = 19647988.

The previous prime is 19647967. The next prime is 19648037. The reversal of 19647989 is 98974691.

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., 12545764 + 7102225 = 3542^2 + 2665^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19647989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19647989.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19647389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9823994 + 9823995.

It is an arithmetic number, because the mean of its divisors is an integer number (9823995).

Almost surely, 2^19647989 is an apocalyptic number.

It is an amenable number.

19647989 is a deficient number, since it is larger than the sum of its proper divisors (1).

19647989 is an equidigital number, since it uses as much as digits as its factorization.

19647989 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 19647989 is about 4432.6052158973. The cubic root of 19647989 is about 269.8398181113.

The spelling of 19647989 in words is "nineteen million, six hundred forty-seven thousand, nine hundred eighty-nine".