1001989 has 2 divisors, whose sum is σ = 1001990. Its totient is φ = 1001988.

The previous prime is 1001983. The next prime is 1002017. The reversal of 1001989 is 9891001.

It is an a-pointer prime, because the next prime (1002017) can be obtained adding 1001989 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 828100 + 173889 = 910^2 + 417^2 .

It is a cyclic number.

It is not a de Polignac number, because 1001989 - 2³ = 1001981 is a prime.

It is a super-2 number, since 2×1001989² = 2007963912242, which contains 22 as substring.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1001981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500994 + 500995.

It is an arithmetic number, because the mean of its divisors is an integer number (500995).

2^1001989 is an apocalyptic number.

It is an amenable number.

1001989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001989 is an equidigital number, since it uses as much as digits as its factorization.

1001989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 1001989 is about 1000.9940059761. The cubic root of 1001989 is about 100.0662560916.

It can be divided in two parts, 1001 and 989, that multiplied together give a palindrome (989989).

The spelling of 1001989 in words is "one million, one thousand, nine hundred eighty-nine".