1990043989 has 2 divisors, whose sum is σ = 1990043990. Its totient is φ = 1990043988.

The previous prime is 1990043969. The next prime is 1990044011. The reversal of 1990043989 is 9893400991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1515544900 + 474499089 = 38930^2 + 21783^2 .

It is an emirp because it is prime and its reverse (9893400991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1990043989 - 2¹¹ = 1990041941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1990043969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995021994 + 995021995.

It is an arithmetic number, because the mean of its divisors is an integer number (995021995).

Almost surely, 2^1990043989 is an apocalyptic number.

It is an amenable number.

1990043989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1990043989 is an equidigital number, since it uses as much as digits as its factorization.

1990043989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 629856, while the sum is 52.

The square root of 1990043989 is about 44609.9090897975. The cubic root of 1990043989 is about 1257.8269399057.

The spelling of 1990043989 in words is "one billion, nine hundred ninety million, forty-three thousand, nine hundred eighty-nine".