1989551 has 2 divisors, whose sum is σ = 1989552. Its totient is φ = 1989550.

The previous prime is 1989517. The next prime is 1989553. The reversal of 1989551 is 1559891.

It is a strong prime.

It is an emirp because it is prime and its reverse (1559891) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1989551 is a prime.

Together with 1989553, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1989553) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 994775 + 994776.

It is an arithmetic number, because the mean of its divisors is an integer number (994776).

2^1989551 is an apocalyptic number.

1989551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989551 is an equidigital number, since it uses as much as digits as its factorization.

1989551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16200, while the sum is 38.

The square root of 1989551 is about 1410.5144451582. The cubic root of 1989551 is about 125.7723065140.

The spelling of 1989551 in words is "one million, nine hundred eighty-nine thousand, five hundred fifty-one".